Dead battery after amp install

Last week I installed my 5 channel amp and two JL 10W1v3-4 in the truck. Install went well and everything seemed to be working correctly, but two days later I went outside to start the truck and the battery was dead. I jumped it and it ran fine. About 30 hours later I tried to start it again and it's dead.

So far this is what I've done and checked:

The light on the amp turns off when the truck turns off.
There's no voltage or amp draw from the remote wire when truck is off.
I pulled the negative battery terminal and checked to see if there was amp draw and it read below 50 mA.

I got all the stuff for my install from James at tech12volts. Speakers are factory JBL, all wired to the amp with the plug from James. For the subs I ran new speaker wire to the amp.

I went ahead and bought a new battery but that was 10 minutes ago. The old battery was the original one. Truck is a 2018 and battery date was 10/2017.

I think it was just time for a new battery but I never had issues with the battery before the amp install.

Anyone have any other ideas what it could be? Or am I just being paranoid and it was just a old battery.