Hi anyone assist with the following?

The external unit is a RXD71JVEA , I have lifted the lid and found a few dead gecko's !!.
Closer inspection indicates that there are NO led's lit, and a component called DB1 it has ~~ and +- label on PCB. (assume this a rectifier)looks as though it has cooked.

Any idea's as to equivalents or what else I should look for that may be at fault.

The overall symptoms of the unit when switched on is that the green light flashes on the internal unit and nothing else. Error code is U4

Thanks