1. reset the waist ink pad by using the steps.
1.a turn of the printer
1.b press the power on button and stop reset button at the same time
1.c release stop reset button then press it four times
1.d this will clear waist ink-pad error.
2. open the scanner by removing the glass over and check if there is a spring that was removed inside all you need to do is bring it back to where it belong to under the light bulb of the scanner, this is the one that would push the light bulb near the glass cover that you just removed.
3. bring back the cover and see to it that all fits well with each other and there you already fixed your canon pixma mp145.