First of all you should not be running any heat source without a thermostat...
thats step number one... get to your local shop or go on amazon and quickly order for expedited delivery a jumpstart or something similar to handle that. You will need two. One for the light and one for the UTH. Those lights can get SUPER HOT. I use one Justin to warm prey and they can easily get to 130 in minutes sometimes hotter.
You also need to get an infa red gun and a digital thermometer. Most of us here use accurate.
You will also want two identical hides so the snake isn’t forced to choose.
What is the temp in the basement ?? Unplug all heat sources until regulated. Corn snakes are strong and adaptable. If the basement is too cold find a room w a decent temp and move the tank there.
Go fill up that amazon cart ASAP and pony up for one day delivery
I do have an infrared temp gun, and the thermometer/hygrometer in there is a Acu-rite Thermometer with wired Sensor model 02067.
The room I have her in is about 55-60.