1996 Nissan Maxima Car wont stay running

My 1996 Nissan Maxima used to run just fine. However I rented out a spray booth and painted the car at a local shop recently. When I picked it up to drive it home two days later I made it a mile down the road when my my lights went dim and the car stalled out. At first I thought I was out of gas so I put 5 gallons in. But then it wouldnt turn over. The battery was dead. I got a jump and left it on there for 15 min to ensure I would make it back to the shop. Now I just put a brand new battery in this car and the alternator was fine before I brought it to this shop. I figured they messed with my connections or the alternator because I had just replaced the battery two weeks proir. Also I never leave the battery cables connected because the car has a draw somewhere and it kills the battery really quickly. So how does something magicly just go bad when the car was fine before I brought it there. I dollyed the car home the next morning and made sure the battery was charged, then started the car to check the voltage output on the alternator. I made sure the negitive and positive on the alternator were tight and proceded to check the alternator. It was reading around 12.8 which isnt the best but it shouldve done the trick. So I let the car run and took the charger off. After about 10-20 min it died again randomly. The battery now read 9.2 so put the charger on it. I tryed starting it up right away but all it would do was make the relays click over and over wildly. So I let it charge and cool down for 15 min and then it started right up again. I left the charger on this time on a 12v 10 amp charge to see how long it would run and it died after 10-15 min. I thought mabey its the coolent temp sensor becuase it seams to be dieing after it heats up completly. So I checked the ohms/resistance of the sensor. It said a good sensor reads about 70-90 ohms and this one was only reading.5 Now I may have been misusing or misreading my tool but I figured that was the problem. I let the car cool back down and re-charged the battery for over an hour. Even with a fully charged battery the car will not even turn over, it only clicks repeatedly for a few seconds then stops. Now I did disconect the temp sensor and try to strat it, not sure if that messed something up but its pluged back in now and it still wont turn over. My battery reads 12 volts and I turn the key all the way and still nothing. This all started happening after I had my car at that shop. However another variable is when I dollyed the car home, I had the windsheild out and I unforchantly got caught in thunder strom. I had gotten alot of water in the engine bay and possibly under the dash. Not sure if that shorted any sensors or ecu out. But I waited 1 week for it to dry out before even connecting the battery after the water was in there. I figured I didnt ruin anything because It did idle for 20 min running just fine before it died. But now its not even turning over, Not sure what the heck happened. Also my gauge cluster isnt lighting up at all. It may have gotten dammaged while in storage durning paint but it used to work just fine before I took it out. Not sure if thats a sign. I know the guys at the shop ended up being not so friendly and words were exchanged after I painted the car. I wasnt to happy when I heard them talking smack while I was painting the car. My dad thinks they used some kinda old school mechanic trick to make these things happen to my car but It could be a huge coincidence. CAN YOU GUYS PLEASE HELP! Sorry for the novel here but I didnt want to leave anything out.