Error 5A means that the purge unit stops abnormally when it is in use. This could be the result of a broken cam shaft. You may have to replace the whole purge unit. Unfortunately this is a job that probably need a technician. If you have not done any troubleshooting then you may follow the steps given below.
1. Remove the power cable from printer. Remove the USB cable that connects printer to computer (remove it from printer as well as computer's usb port)2. Press the printer power button and keep it pressed or hold it down for 2 minutes and then release.3. Now plug in the power cable and usb cable (connect printer to computer) and power on the printer.
Now plug in the cartridges.You may check and see if its works and if the error persists.
As per the symptoms, this is a hardware / firmware failure.The problem is that the printer is not able to complete the initialization process itself and so it will not move further.You need to get the printer repaired : 1-877-BROTHER(###) ###-####(###) ###-####(fax)M-F, 9:00am to 8:00pm Eastern TimeIf not in warranty, it would be cheaper to get it repaired at a local repair store or buy a new one.Feel free to ask any question or concern you may have. I will be glad to help you.
The error is not triggered by the magnetic film encoder strip which you are talking about however you may check of it has not come out of its original position. The encorer strip is located at the back of the print head and its attached both ends to the carraige rail the steel rod which is located at the back.