FP4 Device won't boot in locked mode after /e/OS install

• /e/OS version: 3.3 (A15 community)
• Device model(s): FP4
• Impacted Application: ~
• Affected application/URL:
• Browser/client and version:

The problem

My issue is quite similar as the one indicated here: #5107 (closed)

However, as far as I've seen, the version installed from /e/OS has a security patch indicated as being 2025-12-01 and the one that I had on my phone was 2025-11-05, so there shouldn't be an issue...

In summary, everything went fine with the installation. The phone boots correctly in /e/OS before the step of the the "fastboot flashing lock".

After doing that step, the phone always boots in bootloader mode whatever I do. If I then unlock again, it works fine.

Technical details

Paste any relevant logs (adb logcat) in the codeblock below if you have any