N-channel enhancement mode power MOSFETs.

Pins;
1 2 3
G D S

You definitely shouldn't be seeing 0 ohms across pins 1 and 3. I'm concerned that perhaps the MOSFETs themselves aren't blown but maybe something that was in parallel with them. Can you remove one from the circuit and check the resistance across the pads? Also can you confirm the resistance between pins 1 & 2, and 2 & 3.

The gate failure mode of MOSFETs is usually static related, not heat related. The resistance between pins 1 & 3 should be in the region of 200 - 2000 Megohms. Most 'meters will just show this as infinite. Even if the gate- - drain voltage was 20V, the gate current would still be less than 100nA, (100 x 10^-9 A), ie not enough to do any damage.