PIXMA MG3520 - Error lamp and On lamp flashing

[JL93]

Error lamp and ON lamp flashing.  7 error light flashes followed by one ON flash.  Print cartridges won't align with cartridge opening.   

[DerrickL]

Not sure what you mean by print cartridges won't align with opening? The carriage is in the wrong position? 

7 flashes

The FINE cartridge is not installed in the correct position.

https://youtu.be/FUsYXAToBAU 

I own an MG3620 which loads cartridges the same exact way.