Hi Michael.
I use a PG58 and no heat problem for me, perhaps you need to change the cable, be sure also of your settings:

In Utility > Settings > Audio I/O select "Mic" for AD Input, this is a Common Montage setting. :

In performance > Edit Common > Audio In, select the good connexion L or R mono, depend where you have plug your mic :

In the same windows, adjust the mic Level in the Volume pad :

You have this two settings in "Audio In" window for each performance, so you need to adjust it for each performance you want to use you rmic.

If you always find your level too low, remember you have two insert FX for your AD input, use one of the 3 compressor type or in "Misc" category the "Noise Gate + Comp + Eq", it will help you to increase your level, but don't push too much to keep a good quality.
You can also increase your mic volume in Audio in > Eq, there is a output level, you can increase it up to +12 dB.
This setting is also adjustable for each performance.

Hope it's help.

It would be strange if there was some damage due to an over-temperature event. The MIC produces voltages in mV and impedance is shown as a minimum 150ohms. Montage doesn't supply phantom as far as I know - but a phantom powered environment is about all I can think of that has a chance of causing any damage - and that would be if the short was at the cable end near your MIC or short internal to the MIC.

You should be able to measure the impedance between pins 2 and 3 of your SM58 and expect something around 300 ohms (measure resistance). Below 150 and above 600 should be considered a fail. Discount tool stores have ~$2 meters that will handle this task.