Your heat mat is in the enclosure?
your uth or heat mat needs to be on the outside bottom of the tank regulated by a thermostat. No if and or buts about it. Do not use it if it does not have a thermostat.
I use a jumpstart bought from Amazon. It's the green one. I also use an accurite digital humidity and temp gauge. The grey one.
Post a a pic of your set up for us to see.