G4 1.0 MDD 2002 not turning seems dead no signs of life

[radioteur]

Hi, guys long time no see.
 I'm back here  because I think I've done the stupidiest thing in my life and need some help, I forgot to remove the power cable from my MDD DP 1,00 OS9 dedicated and started switching hard disks , removing some pci card and ram briefly I made some works on the MOBO. Well,  I usually do this  thing after removing the power cable from the power supply...but not this time because my mind was on the clouds. No need to add that my beloved G4 it's not turning on, no lights no signs of life....please don't say it's dead...am I forgetting something? Is there any chance it is not fried up? How can I check?

[torvan]

Not sure what "made by some works on the MOBO" is meaning, I assume you mean you did something on the motherboard--what was that something?

But if there is no sign of life:

Make sure you did not flip the breaker by accident. On the back is a red 110/220 switch, so make sure it is set to the right voltage for your country.
Try a PMU reset which you can see at https://support.apple.com/en-us/HT1939
Try replacing the 3.6 volt 1/2 AA lithium battery.  Know it sounds odd, but sometimes that is the case.
Try pulling all the cards out of the machine and see if you power up.
Try to generate a RAM error now, pulling all the RAM and Boards.

Finally, if you have a probe, you might check the motherboard for power and the power supply as you might have killed off a fuse. The full service manual you will find at http://tim.id.au/laptops/apple/powermac/pmg4_mir_fw800.pdf