Make sure you haven't damaged any of the legs on the chips when re-inserting them and they are all in the correct way around. Look for the notches on the chips. You should have also re-inserted them in the same positions as you removed them - but you probably know that already!
Sounds like one of your colour input wires is loose / not connected or one of the colour transistors on the neck board has died. Get the teswt screen up on the 60 in 1 and see if either red, green or blue is missing / incorrect.
I recently got (another) Ninty cocktail to gather parts for a Space fever resto.
I now have a pcb, but it just has bars of coloured lines on the screen.
I have been told that it may be one of the 4116 rams or an ls174 that is the problem.
I probed all the rams in the line to compare and one of them at I5 is different on ppin 14. I am just about to whip it out, fit a socket and try another 4116 ram (that hopefully works, but has not been tested)