I have been given acer 5100 and pressing power button it light momentarily and goes off. It will not boot anything, until I press power button and then hold down F9 or F10 keys then it will boot as usual and things goes well. I have even upgraded the bios to latest 3.1.3.
I'm running out of ideas and I thought I would ask. Since I'm not sure what the issue is then I though I would post here

I've read that some of that model have faulty hard drive connectors and won't work until the POST tests are bypassed.

I would try changing your boot order because you never know; maybe the bus connecting to the HDD takes a few extra moments to get on-line causing boot to normally fail, or maybe you can bypass some tests through the BIOS.

This is the manual that includes troubleshooting and how to disassemble/reassemble the computer: ftp://ftp.work.acer-euro.com/notebook/aspire_3100/manual/aspire_3100_5100_5110_en.pdf

Thank. The ownerdecided would go that way, start with F key pressed. I adviced to go that way since there is no fix and it does not hurt anyway!