I have an Inspiron 1150. It shut off whenever tapped or moved...even if just repositioning for more comfort.
Found out it has a design flaw...
following is a quote:
In short, there is a design flaw between the motherboard and case. The
mini pci cover underneath (below DVD/CD drive) and labelled 'C' has
plastic tags in the centre and any pressure applied to the underside of
the case - for example when picking up the laptop by the front left
corner - causes this cover tab to press on a motherboard IC (chip) and
eventually fracture the solder connections or maybe damage the chip
See this site for the hundreds of people with the same problem. Much of
my info came from here.
Like I said, the link doesn't work, and you didn't say anything about removing parts or pegs in your original post. From what you said, the only thing I gathered is that you took off a plastic panel, flipped the panel over, and removed some piece from it, then put the panel back on.
Do you have pictures of what you did?
At any rate, remove the optical drive and the battery and try to boot.