How do i downgrade firmware on my brother printer
I have just made the same mistake on my Brother MFC-J470DW printer. I allowed it to upgrade the firmware, and two of my ink cartridges, which were previously nearly full (and not OEM original equipment), started to display as "Cannot Detect" on the printer display. I contacted Brother and they directed me to a site that basically says you HAVE to use original Brother ink cartridges after the firmware update to version H.
In other words, Brother has found a way to limit our machines so that we cannot use non-original ink cartridges. I found a way to work around this problem, but it only works because I have the original cartridges that were nearly empty. You can carefully open the plastic case of the cartridge, being careful to note where the springs are located and to not lose them. Then you can see the reservoir for the ink. You can use an empty syringe, minus the needle, to suck out the ink from a non-oem cartridge. You have to press the upper release prong (spring-loaded thingy at the top of the cartridge) while you suck out the ink into the syringe at the bottom port of the ink cartridge. When you see that the cartridge is empty, reverse the process by squeezing the ink into the original Brother cartridge in a similar manner. You don't have to open the cartridge to do this, but it helps to see the levels of ink before and after.
Hopefully Brother has not found a way to make their ink clash with compatible inks so that they damage the printing ports of your printer. I haven't done this on this machine yet, so be careful, because you might destroy the printer so that you cannot even use original inks anymore. Personally, I bought the printer on sale at Staples for $50, over a year ago, so if I ruin it by mixing oem and non-oem inks, then I will just buy a different brand next time and hope for a more ethical company policy on allowing non-oem inks (compatible inks).
On this printer, I have used non-oem inks ever since the starte inks ran out. They always work just fine! I get them at Meritline.com. Make sure to read the comments at meritline.com because if you have updated your firmware recently, then Brother has made it impossible for us to use non-oem inks anymore. They do not offer a method to downgrade the firmware! And I cannot find a site to find the older versions. The only download they offer is a firmware upgrade tool, and not the actual firmware versions.
Hope this helps.