Just bought a preowned 2011 GS350 AWD on 3/22/24. The short version is we replaced both key fob batteries and tested both on doors locking/unlocking thinking we were good.

After doing a bunch of preventative maintenance and cleaning, drained and filled coolant, then took it for a first test drive, returned home to the garage, shut engine off and dash
instrument panel saying "key not detected". We spent the rest of Saturday 4/6 trying to clear the message and research it, but had no immediate answer that night. So, to stop the message from appearing, I kept one of the key fob in the car in the garage overnight to keep the message off, and the next morning, the car would not turn over, only the accessory lights dimly appeared.

So Sunday morning, 4/7, I ran out to walmart to buy a new $150 Everstart battery, installed it, started up the car, took it for a second test drive since owning it, put it back in the garage engine off, and key not detected message still appearing. Searched for a fix all day long, still nothing. Monday morning, 4/8/24, wake up to a brand new battery completely drained, with no lights on or any power at all.

What is going on here? This is my second post and shortened version, my first post never appeared, I could use some guidance, hopefully this message will post this time!