My Canon 5d mark2 is noisy after replacing circuit board

[prpich]

After having the circuit board replace from canon repair that was to fix the USB port. Now when I shoot tethered there is a lot of noise in the image . It looks like geometric squares when enlarged to 100 % +. I photograph a lot of fabric and this pattern shows up and the image. And is not usable. Has any one had this problem?

[cicopo]

Sounds like there's a bad connection between a socket & the plug on one new circuit . I'd send it back with a very detailed description of the problem & how to replicate it.