Flickering 3rd light, alarm going off randomly, and heater not shutting off when vehicle is not runn

2017 toyota tacoma trd sport;
So upon shuttinf off truck, heater stayed on 5 times then in between those it shut off with the truck. Powered back on and turned off again, heater stayed on.
Last night alarm went off twice in the middle of the night. Replaced battery in Fob. So far so good fingers crossed.
3rd break light had the Warrenty work done about 3 years ago, this year the battery has been dying like crazy but once returned to shop it shows full charge. Now 3rd break light flickers everynow and again.