I am trying to repair a QNAP TS-251+ NAS system which doesn't boot anymore.
I checked all voltages on the PCB and the power supply seems to be fine.
The management engine seems to work, it lights up the LEDs when I try to turn it on.
It originally comes with the AMI-Aptio DT (c) 2006 FE68 9571 BIOS.
The CPU is a Intel Celeron J1900 (SR1UT, Quadcore, 2GHz with Intel Graphics, DDR3L RAM)
I dumped the original BIOS with the flashrom tool on a Raspberry Pi, this is the 8MB image:
futureware.at/~philipp/GRAQNAP.dat
I tried several different BIOS variants I could find for the J1900, and one of them had the behaviour that it was beeping when I unplugged all DRAM.
The other BIOS images did not seem to have any effect.
I did not see any Network traffic from it and I couldn't get any image from the HDMI output.
Is it possible to verify the integrity of the BIOS image? (Does it have checksums? Which tool should be used to check them?) Could you check the Bios image for me?
Does anyone have a BIOS image for this QNAP device that I should try?
Thanks a lot for any help and for all the valuable information on this forum!

Edit by Fernando: Thread title specified and customized

Bios file (QW37AR32) seems ok, theres a new bios QW37AR33 file and some recovery details here: https://forum.qnap.com/viewtopic.php?t=133898&start=30