iPower 6 by 8-Inch Reptile Heat Mat

I have bought a ton of iPower branded stuff since 2016, from large inline fans to hi-wattage bulbs, etc: Never been disappointed with a single one of those purchases. So when looking for a tank heating pad for my sons two hermit crabs and I found this iPower product, I bought it straight away. The 8"x18" iPower Terrarium Reptile Heating Pad Under Tank Warmer Heater Mat with Digital Thermostat. The packaging, and listing, claim the 8"x18" size is for "50-60 Gallon Tank Use". We would be putting it on a 10 gallon tank. I bought mega-oversized for our tank because we live in a cold climate and indoor/room temps can get down to 65 degrees in the winter. Figured bigger is better and the controller will moderate (what I thought would be a high output heating pad so we wouldn't have to worry about cooking the poor hermies) the temp anyway. Tank is even half full of sand (at room temp of 68 degrees and the air in the tank can't get warmer than 74 degrees). I attached the pad on the back of the tank using the 3M adhesive installed on the pad, taking up the entire back glass from side to side and 2/3'rds of the height from top to bottom. Normal type install for hermit crabs and we set the temp probe for the thermostat 3" from the back wall/heat source. I wanted no more than 85 degrees at the probe, so set the thermostat to that temp. Never even got close. It's been more than a week, certainly more than enough time to have been given a fair chance at functioning. Can't get heat at the probe to be more than 74-76 degrees. Even an inch away from the pad at the top of the tank -where it should be the warmest-, we have a humidity meter/thermometer and it hasn't gotten warmer than 77 degrees. At the time I took the attached pics the ambient room temp was 68 degrees, the thermometer was reading 77 degrees and the probe reading was at 72 degrees. The sand at the front bottom of the tank, furthest away from the heat source, was 68 degrees/ room temp (taken with an infrared thermometer). The pad wasn't producing any decent heat, anywhere in the tank. This heating pad simply doesn't work as it should. I will be sending it back if I can. I just hope i can get it unstuck from the tank, because the adhesive is the only thing that does seem to be working. I'll keep buying the other iPower stuff I've bought before, but this item is a piece of junk.