My Acer laptop (5520) does not boot up. Had similar issues last week but managed to get it working eventually (no thanks to Acer Support).
I now have the same issue:
It doesn't boot up - last night managed to get the Use Safe Mode screen - but no further. Next time it was the Startup Repair screen. I started that and then it shut down.
It now powers for a couple of seconds and then powers down and then powers up for a couple of seconds and then powers down and the cycle continues.
I have tried running it from battery only - no difference. I then tried AC power with battery out - no difference.
Any ideas would be appreciated.