Airbag fault light on.

[The Tall man]

Hi guys. Hope everyone is well . After having fixed my ABS light fault with the help of you guys, My airbag light is on and not for going off. I've tried the usual method of checking the connections under the seats. I've removed the connectors and just soldered the wires together. No joy light still on. I've checked under the carpets for water ingress but both sides are dry and visually the side impact sensors look ok. I've removed the steering wheel to look at the airbag connection but again it looks ok. I know they could have a fault. I've now removed the airbag ECU next to the handbrake. again its all dry and looks okay. So Now I've bought a second hand airbag ECU from Ebay and waiting for it to arrive. Does anyone Know if I have to get it set up at a garage or can I just plug it straight in. I'm stuck with the light on and the MOT is due in 2 weeks. Any advice would be welcome.

Many thanks. Alex.