Heating concerns for Western Hognose snake enclosure

[PAHNKAPIE]

So I bought a 50-60 heating pad zoo med brand for my enclosure and stuck it to the bottom of my tank with a heat probe between the tank and the pad. The heat probe won’t let it heat past 108 degrees. However the interior of the cage is reading only at 69 consistently. It’s been like this for a few hours not going up or down. I don’t know what on earth to do I need the warm side to be like 80 degrees. The pad is adhered to the bottom of the 40 gallon tank and I already have all the substrate in the tank as well. I can’t Tip the tank on its side if I have to remove the pad and stick it elsewhere (if it even would after being stuck once) I’m kinda panicking that I might have to buy an all new heat pad or something idk. I feel like I’ve already just about broke the bank and I don’t even have the snake or the decor inside the tank purchased yet. Can someone please help me? Again I have one temp probe that keeps the pad from getting too hot between the pad and the tank. I have another probe just hanging in the warm side of the enclosure to measure the ambient temperature on the warm side. I can only set the heat pad to 108 degrees (that seems to be the thermometers max) but the ambient temp in the warm side is still only 69 degrees x.x which is only two degrees warmer than my room sits at currently. I’m also worried about how much electricity it’s going to take to keep this cage warm if one 50-60 gallon heating pad isn’t going to cut it.