Siemens MXL panel. I have a loop that is not responding

Loop is not responding to Mxl panel. All devices in loop have been dropped out completely. Smokes, thermals, and pull stations. No voltage at devices. The PAD has the required 110 volts, batteries are good, and I do have 24volts at PAD. We did have a storm and a brown out few hours prior to when devices went into trouble. Checked for moisture in devices and they visually looked dry. They went out of trouble for about 8 hours and then came back in trouble. No rain or storms from devices going out to back into trouble.

Also checked all smokes for moisture and there was none.

I would go down the whole loop in order (best you can if you don’t have a map) and pull each device down. If you have power at the panel, you should have power at the first device. If this happened after a storm, it’s possible a surge took place. May just have one device in the loop that’s shorting and dropping voltage. Otherwise, could be looking at a panel replacement.

Do you have 24VDC on the SLC? It will fluctuate from around 20 - 27VDC if it’s good. If no voltage on the SLC then the circuit is either shorted or fried.