If you are putting a Raspberry Pi in your machine, Whenever you make any type of significant process, make sure to back up your card. I can't stress how many times I had to reflash my card due to a novice coding addition that pretty much stopped me from progressing. If you are drilling additional buttons, Take your time and measure your holes, do not rush it. Remember you are sticking the buttons in there with washers, make sure there is plenty of room for those as well ( I almost screwed up my Raph buttons by drilling the holes too close together). Don't be scared to improvise as well, I've modded my TMNT cabinet to the ends of the earth (See my profile). Once I learned how to drill holes, I became power tool crazy and started drilling holes all over the place and making some cool mods on the way. Also just a tip, If you want to replace the power switch, you can use this one (Ofcourse if you're putting a raspberry pi in it only), It fits perfectly in the "on/off" hole.
Edit: Grammer
Did you look at the wires and end points? Could be just a loose wire or chafed insulation. It'll be easier wiring your own power switch(Something like this) rather than trying to get help from thermaltake.
I did this when I tried to hide my pc behind a bench and wanted a switch to turn it on without reaching out to the pc’s power button. Bought switch here - https://www.amazon.com/dp/B07PPDHKDT/ref=cm_sw_em_r_mt_dp_TNAST03DTJP1GGH0STYX?_encoding=UTF8&psc=1. Had to cut to extend the wires cause it’s too short.
When using a PC, you can probably just wire a power button to the power switch pins on the computer's motherboard. Something like this.
https://www.amazon.com/NOYITO-Chassis-Extension-Suitable-Computer/dp/B07PPDHKDT/
And just mount it wherever is most convenient for you on the cab.
You can buy a cheap external power switch. There are dozens of varieties.
https://www.amazon.com/dp/B07PPDHKDT/ref=cm_sw_em_r_mt_imm_awdb_7RREF98KX4CZKC5J8D1X
Just connect a separate switch to your pc and keep it out of her reach
NOYITO 16mm Chassis Switch Metal... https://www.amazon.com/dp/B07PPDHKDT?ref=ppx_pop_mob_ap_share
yep! this is how desk pcs are normally done.