My 94 Q45t recently stopped working and there's no power to anything in the vehicle. I bought a new battery and everything seemed to be working fine but after just overnight nothing is working again. I replaced the relays connected to the battery cables but that seemed to not work. Any ideas if something is registering as on? All my lights and everything was off overnight and the battery seems to be dead

Make sure you aren't suffering from a bad connection and not a dead battery. Measure voltage from post-to-post and then cable-to-cable, if the voltages aren't near-identical then you have a bad contact somewhere. If the connections are good, common "invisible" draw culprits are glove box lights, trunk lights, mirror lights in the visor, bum radios, and bum alternator diodes (probably in that order). If you don't find any of those, it's time for a draw test.

I tested the voltage between posts and it was jumping up and down while the car was off. The before mentioned relays had some corrosion and I replaced those which fixed the spiking voltage between posts. I'll try the cables and go get the battery tested at an auto store. Would any of these "invisible" draws be able to seemingly drain a new battery just over 12 hours?

Yep, even a small peanut bulb draws a couple of amps. On a new car with LED's maybe not, but any incandescent bulb will suck a battery down fairly fast. Bad alternator diodes usually draw 2A+ and bum radios will draw 1~5A. So yes, any of those could cause a dead car in the morning.

If you disconnect the battery cable and measure the amperage between the cable end and the battery terminal it will tell you how much current draw there is. Pulling fuses one by one will help identify the circuit that's causing the draw.

Thanks for all the help guys. Need to get a ammeter or whatever it is and get something to charge the battery cause it completely died. Will update if I find the issue.

Most multimeters can measure small amperage levels, like what you'd have as a parasitic draw.

This is my "beater meter" at the shop, it's an excellent tool for $30 and Walmart usually has it on the shelf:
https://www.walmart.com/ip/Hyper-Tough- ... /815000129

I would watch some youtube videos on testing "parasitic draw"

You should be able to narrow it down to a circuit by removing fuses and seeing the load drop. I checked mine earlier in the year, so for reference on a 1990 Q45 with the hood switch disconnected (simulating having the hood closed) and car locked with the key only, my load was 28mA. With the hood open and the hood switch connected, the "security" light flashes on the dash and the load pulsed between about 70 and 170mA, averaging at about 120mA. When it was locked with my aftermarket Viper alarm on, I had about a 170mA load.

She's a garage queen, so I ended up buying this https://no.co/genius1.