Anrtisu SiteMaster S331L stuck in Loading OS mode

[EIKA]

Hi all!

I come across with a problem. When I tried to upgrade firmware on my SiteMaster S331L from 2.90 to 4.00, process failed with error message: Could not find file V4.00_SM-L.bin. Even when that file in place.

Now device shows:

CPL V1.4
Loading OS… Anrtisu SiteMaster

And stuck in this mode

I believe that problem can be fixed via forced bootstrap mode, but sadly I can’t fine information how to get there in S331L model. S331E model offers Shift + 4 + 0 + Power On for this mode, but L model has no Shift button.

Any ideas?

[EIKA]

S331L forced bootstrap mode (secret key combination, never described):

Connect external power supply
Turn device off
Hold down 4 + 5 + 6 and briefly touch Power button (for 1-2 seconds). Then, release Power button, but keep holding 4 + 5 + 6 .
Here you go - bootstrap app will load in 15-20 seconds
Use Update firmware button then

P.S.
WARNING! Do not use huge USB sticks with S331L. 32GB sticks and especially PNY sticks might kill your device during FW upgrade. Use 8GB or smaller sticks from SanDisk or Kingston.

[dannyazs]

Thank you, The solution worked, and its probably the same on the S820E as well. Really unfortunate that anritsu wouldn't include that into any of their manuals or update procedures, unless i missed it somehow. Been looking into it for a few hours and the manual only specifies that the SOM or main PCB need to be replaced.