My Canon 6D is not working properly

My Canon 6D is not working properly. I noticed my coloring is off, pink tones. I also have trouble shooting in low light with a 50mm 1.4. It is like not enough light is coming in even though I know there is. The images are blurry and and coloring is off. Every time I search this it says user error, I have manually set all my settings. My partner who does photography with me tried and she can shot fine with all the same settings and lens but my camera will not budge. Took it to repair shop, they said either communication error between the sensor and main board or main board is bad. Any thoughts?