Hey there TN3500, you haven't given us any details. Here's what your friends are saying:
1) You don't have to disconnect the battery, but if you like to be extra safe, you can. It shouldn't make any difference unless you short something out while wiggling wires.
2) You should NOT reuse the PMD/FSD - you should use a new one. If you were having problems with the PMD on the pump, "Remoting" it will not cure it. "Remoting" simply avoids the damage. If it already has damage, you can't cure it that way... hence the call for a new driver.
3) Your best best is to buy the Heath Remote FSD solution - it comes with a warranty, and has proven very reliable.
4) IF you decide to build your own, then you need to use a new driver, get an appropriately-sized heatsink, either buy or build a decent extender cable, follow basic rules (e.g. keep the ground wire in place), and make sure you connect the FSD to the heatsink properly - (e.g. use of proper thermal compound, proper torque sequence and torque amount, proper weather sealing, etc.).
You're just not giving us enough info to help you.
Based on what you have written so far, I think you must be re-using your old FSD, which is fried. You need a new one!
-Rob
