crack open the new pc and tap into the power on cables /switch.
if you managed to splice / tap into the previous set-up then i'd reccomend you do it again. remember you didnt damage the last one through any fault of your own , it was the weather that did that for you.
having an open pc within a cab isnt harmful , provided you have taken proper basic precautions that is . but just because a wire is spliced or modified , it doesnt mean its attributing to the breakdown or frying of components. the only thing the power switch and its wires are supposed to do, is send a signal to the psu to switch it on. no more no less.
also, have a look at the fuses your using in your plugs. ( power strip too ).
if your pc psu is a 500w model for instance , then change the fuse to match your voltage. eg - if you have 120v power , use a 5amp fuse in the pc plug , 5Amps x 120volts = 600 watts.
then try to match the total power draw on the strip. eg - pc / monitor / speakers / = average of 1,200 watts draw, or there abouts , so use the likes of a fuse which can handle that combined power , eg a 10amp fuse . 10amp x 120volts = 1,200 watts.
if your a uk user , it works like this : 5amp x 230volt = 1150 watts.
this can help from further lightning damage if your worried about it , but a good power strip with proper protection should save any attached appliance. only use compliant power strips that guarantee you 100% protection and dont buy power strips that are cheap or in bargain bins.