Faulty Inverter

Hi

Ok so I though maybe that it was the low voltage protector or the surge protector and tried it just now to check if the protectors might have done a reset. When I contacted the 50ah battery the damn thing popped in my hand and nearly electrocuted me. I did check the fuses on the side but they did not work as they where designed to do

Please tell me the path forward as you sold me a thing that's a danger to my health

I paid the delivery cost for the package and now you want me to courier it back to you also to my cost. I think this is unacceptable

Regards