On my bunker when you press the button that turns it on if you wait for about 20 secs it turns to freezing lava I don't know what causes it can somebody please help
Heat simulation has been turned off. TPT will then stop simulating heat. The burning of a small quantity of dust causes it to melt. The fire does infact not have enough heat to melt the metal but as TPT has stopped simulating heat it melts. Again, with no heat simulation the lava will simply melt more metal.
By the way, the spark powering the shields are burning the stuff inside. The surroundings are so cold that stickman would freeze to death, using liquid nitrogen continuously is much like using a chainsaw to open a bag of chips; it's over kill. Also might I suggest you work on your set out: it looks like it's already been bombed. And don't use CLNE or PCLN in a bunker, they're partially indestructible thus ruining the whole point of the bunker.