Help mk4 tdi seat ibiza fr 130 pd power streering fault

[Dirty Ibiza]

Hi, i am just wondering if anyone had any idea why my Ibiza keeps cutting all electrics off while driving and then to start working again, apart from my power steering that will turn off until i turn the car on and off.
replaced battery around 4 months ago,also replaced 2 battery earth cables which have broken right at the connector,the wire looks almost like it was cut...no signs of burn ect...scanned it and got 4 faults as below....

00778 Steering angle sensor - upper limit exceeded
00566 Steering assistance operation - open circuit
01288 Terminal 30 steering assistance - short to pulse?
00929 Lock unit central locking nearside front


any help would be grateful and maybe some ideas on what to do next? what to test first? hopefully ive posted this in the right place and maybe this can help other people searching the web , Thanks