Filled the block .. how to safely check its operation?

Question

Uninterruptable power source

I have such a protective power supply for imac.

spoiler

I took water into a bottle, half a bowl is so
plastic, went further to bend, put it next to the mouse and knocked the bottle onto the block with one stroke, but I reacted and quickly cut everything out, pulled everything out of the sockets .. the table was in the water, the poppy stand too, but more important all this power supply, I’m very afraid to continue working with it, but it seems that water didn’t get on it, because I said that for some reason it quickly reacted ..
So ..

How to safely check the operation of the power supply without loss?