Gear box fault message

[Jaguar_xj8_v8]

From the last time wrote ,I hadn't had much luck fixing the issue. 

The a re cap , bought a jaguar xj8 1999 4.0 low mileage, only had restricted performance due to coil pack . But decided to remove a resonator on the exhaust to see if sound changed , after the job was done I started the car and it was in gearbox fault , noticed the s mode button is constantly on . 

IV changed the valve body , gearbox service, changed all earth grounding points and gave it a rough look over still in gearbox fault mode. Iv have taken it 2 Jaguar so called specialist and they are confused. 

I'm thinking what's the worse that could have happened? Bad earth welding, possibly blew a fuse ? All fuses are working fine.last time I plugged a genetic code reader it came up with cam shaft bank 1 lambda bank1 gearbox fault shift solenoid c I think , but IV changed the valve body code disappeared and came back a while after. Car had a new battery 780cc 95 ah I believe.