Request] Stylo Horizon (EBY33) Unisoc SC9863A Stuck in "No Valid OS Was Found" / BROM
Request] Stylo Horizon (EBY33) Unisoc SC9863A Stuck in "No Valid OS Was Found" / BROM
19-07-2026, 07:48 AM
Hello Hovatek Team,I am working on a Stylo Horizon (Model: EBY33), which is a budget South African device running Android 13 on a Unisoc SC9863A chipset.The Problem:The phone is currently stuck in a bootloop. After unlocking the bootloader, it displays a small error message in the top corner of the screen: "no valid os was found" and restarts continuously back to the Stylo logo.It does not boot into Android, and I cannot force it to stay in Fastboot mode.Tools Available:Chimera Tool (Active License)Infinity CM2 (CM2SP2)UnlockTool (Active License)SPDClient (Python tool)What I Have Done & Current Blocks:Resets & Erasing: I managed to successfully run a factory reset, erase misc, and erase metadata via Chimera Tool before the current handshake issue started.The Dump File: I sourced a reputable raw dump folder for this phone. However, the dump contains split .img files and a special folder containing a unisoc_partitions.img. It does not have an official .pac file, nor does it contain individual fdl1.bin or fdl2.bin files.Low-Level Handshake Failures: Now, when I try to flash or read the device partitions via BROM mode (holding Vol Down with battery disconnected), multiple professional tools fail at the exact same stage. They send the initial payload but time out when booting the internal eMMC storage loader.UnlockTool Log:textFLASH Selected Platform : SC9863A_32_Bypass
Waiting for device... COM18 (SPRD U2S Diag)
Initializing loader... OK
Protocol : SPRD3
Sending payload... OK
Sending auth data... OK
Sending preloader1... OK
Sending preloader2... OK
Booting loader, please wait... FAIL
Protocol : Failed to handshake with device!
UNLOCKTOOL 2026.07.09.0
Use code with caution.CM2 SP2 Log:textboot iLoader... Ok
run iLoader... Ok
boot xLoader... Ok
run xLoader... Ok
Bootcode Handshake...
PORT Tx 0x79 The semaphore timeout period has expired Fail
Use code with caution.My Questions for the Forum
oes anyone have a factory-signed .pac firmware package or working FDL1 / FDL2 loaders specifically matched to this Stylo EBY33 motherboard variant to stop the BROM handshake crashes?Since the phone rejects generic SC9863A_32_Bypass exploit loaders, how can I successfully flash my blank/patched vbmeta.img to bypass the "No valid OS" security block without triggering a connection drop?Can I use the unisoc_partitions.img from my dump folder to reconstruct a flashable scatter/XML format that tools like SPDClient or ResearchDownload can process?Any guidance, custom loaders, or stock pac links would be highly appreciated. Thank you!
01-08-2026, 11:59 AM
(19-07-2026, 07:48 AM)Mugeri ..My Questions for the Forum
"No Valid OS" points to an AVB issue...unless you had tampered with the super partition (or its components)
1. How did you unlock the bootloader? Which method/tool performed the task?
2. The device is unlikely to accept a blank/patched vbmeta (not 100% certain though)
3. Can you share a link to the dump you have so we take a look
Hint: Have the battery connected (not disconneted) when using the tools. Also try button combos like both volume buttons and power + both volume buttons
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02-08-2026, 03:09 PM
06-08-2026, 06:57 PM
(02-08-2026, 03:09 PM)Mugeri I unlocked the bootloader using Chimera Tool while the device was still partially booting...
It's a Pandora dump and very usable. You just needed to make a backup using any of the tools you had, keep a copy, then swap the files with what's in the Pandora dump, then restore.
Unless Chimera's FDL was incompatible or it wrote a blank/generic vbmeta, the handshake issue might be a driver thing.
Check Device Manager for what the device is detected as and uninstall it (tick the box to remove). Then hold the boot key and connect to the PC. That should reinstall the drivers. Then retry reading info.
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06-08-2026, 07:46 PM
The Pandora dump has not fdl files, Chimera tool has been connecting without a problem. The issue I am facing with Chimera is partition mismatch on both the original backup I did using Chimera and the Pandora dumb. CM2 what giving me connection errors and I used fdl file from ZTE which has the same cpu. I swapped files using cm2 and it gave me white screen with invalid OS. I learned about partition sizes, length, and addresses from your MTK class ut the problem is wwr doesn't work on this chipset. I wanted to rebuild a pac file and include the fdl files from zte.
06-08-2026, 07:48 PM
(06-08-2026, 07:46 PM)Mugeri The Pandora dump has not fdl files, Chimera tool has been connecting without a problem. The issue I am facing with Chimera is partition mismatch on both the original backup I did using Chimera and the Pandora dumb. CM2 was giving me connection errors and I used fdl file from ZTE which has the same cpu. I swapped files using cm2 and it gave me white screen with invalid OS message. I learned about partition sizes, length, and addresses from your MTK class but the problem is wwr doesn't work on this chipset. I wanted to rebuild a pac file and include the fdl files from zte.
06-08-2026, 07:49 PM
(06-08-2026, 07:46 PM)Mugeri The Pandora dump has not fdl files, Chimera tool has been connecting without a problem. The issue I am facing with Chimera is partition mismatch on both the original backup I did using Chimera and the Pandora dumb. CM2 was giving me connection errors and I used fdl file from ZTE which has the same cpu. I swapped files using cm2 and it gave me white screen with invalid OS message. I learned about partition sizes, length, and addresses from your MTK class but the problem is wwr doesn't work on this chipset. I wanted to rebuild a pac file and include the fdl files from zte.
11-08-2026, 11:09 AM
(06-08-2026, 07:46 PM)Mugeri ...Chimera tool has been connecting without a problem....
Try choosing other models with the same chipset in these tools, which sometimes bypasses these errors.
Run a quick test; try reading info or backing up any small partition using the available tools. Let's see if it's still stuck at the same stage as flashing.
Learn MediaTek, Unisoc / Spreadtrum (SPD) and Qualcomm Software Repairs @ https://www.hovatek.com/training
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