Hi,
Probably no need to pull the wheels to discover the problem, though you might need to pull off the wheel (where you had the blowout is likely) to repair the broken wire.
Look for a wire that goes into the 4 hubs under the trailer. You will probably find one that is damaged, or a connection that is preventing any of them from getting power. Fix that damage, and all should start working again.
You can test with a compos. Have it near a tire, and someone apply the brake manually in the truck. The needle should swing towards the rim, indicating the magnet is working. Of course you already know right now that none of yours are working, you will need to repair them first.
Also do not leave the emergency brake on very long. The magnets will have a full 12 volts applied to them, and they can overheat the coils, melting them. In normal use, only about 2-8 volts is applied to the magnet to apply some drag against the hub, and apply the brakes lightly pressure. It is only in a panic stop or the emergency switch is activated that full braking pressure is applied with a full 12 volts.
If you need more parts, try this place.
eTrailer.comFred.
Money can't buy happiness but somehow it's more comfortable to cry in a
Porsche or Country Coach!
If there's a WILL, I want to be in it!
I havn't been everywhere, but it's on my list.
Kangen.com Alkaline waterEscapees.com