I have the exact same problem as this with Compaq Presario CQ56 105SL (AMD V140 CPU). Sometimes I can get it to boot by pressing either esc key or f2 key while turning it on.
I have already re-flashed the BIOS to F.18. Removed and re-seated the RAM, CPU and CMOS Battery (also installed new CMOS Battery). Sometimes it will run for a few days with no problem then all of a sudden back to the black screen again. Have searched for weeks on a proper solution but don't seem to be any closer.
LED Blink codes sometimes indicate CPU (1 x Blink, pause and repeat) and other times Corrupted BIOS (2 x Blink, Pause and reapeat) . Getting frustrated now.
Some have said that it can be repaired by re-soldering the graphics chip using infra red but I suspect that the issue is not actually with the graphics chip as when it's running it runs perfectly with no effect on graphics at all. The problem is only when it hibernates or gets powered off completely but again this is only sometimes not always.
Would really appreciate any further information or help. Thanks in advance.
Edited by drdenniss, 22 May 2013 - 09:09 PM.