how about a photo of your device? Did you check whether the transistors work properly?
I may quote myself here:
Usually, electronic elements that aren't smd can withstand quite a lot of heat. I don't think that's the issue here.The transistors might be damaged. Use a diode test, if your multimeter hasn't a tester integrated. Connect plus(red) to the base and minus(black) to C and E, which should give you a value. Any other combination shouldn't. If it does, new transistor(s) are called for.