mac mini won't boot

My mac mini (4 usb ports) wont boot. Nothing happens except white pin hole light comes on and disc drive whirrs for c 30 seconds.
I have reset PRAM and PMU, tried starting in target mode - disconnected everything, forced it to shut down numerous times. Tried to boot from original disc (took in and won't give back hence whirr...). Tried different displays that I know work well - but NO video, no chimes, nothing - is it dead?
Is it worth attempting to recover or should I cut my losses and buy a different mac model...?
Any suggestions appreciated.

My G4 had a similar symptom a few months ago.

Try replacing the internal battery - costs next to nothing and might well be the cure

Radio Shack sell em (or Maplins in the UK)

Thanks. I am not sure how to open up the mini.... it doesn't seem to have any obvious screws...can anyone help?

OK - battery removed - won't boot without it, but I will try replacing it.
Thanks for the suggestion.

it wont boot without it, but my macs power light used to glow and then do nothing

the battery switch fixed it

Have changed the battery - it makes a couple more clicks when trying to start but still wont boot...is this the end of the road???

Does it make the Startup Sound at all? Try holding down the left mouse button after you press the power button and see if the install DVD eventually pops out. Did it just one day not power up? Was it fine before that day?

i've tried holding down the mouse at startup a number of times - nothing. I never get as far as the start-up chimes as it clicks a bit then spins the disc then just goes quiet with the light on. One day it was fine - the next, nothing.
I have tried to get at the disc with tweezers but cannot and I have taken the drive out (when replacing the battery) but cannot get the disc out - although I had the problem before I put the disc in...