Brother MFC-L3770CDW Toner Fix

I recently powered down my Brother MFC-L3770CDW printer after it had been on probably for a year. When it came back up, I had a NO TONER error (not a "low toner" error). The toner was definitely nowhere near empty, but the printer simply didn't recognise the toner. I pulled the cartridges out and put them back in, but that didn't help. These toner cartridges are not the genuine Brother brand cartridges, but they had been working fine.

I then found this Reddit post which talked about checking the battery in the toner itself. I had no idea, but in fact each cartridge has its own battery.

If you take the toner out you will see the contacts of the "chip." You can slide the chip out by pressing gently to the left (in the picture to the left) on just the chip. When it comes out you will see that in fact there is a battery there.

It was marked LR521 which is also the same as an AG0. It's a 1.5V battery for watches and as you can see in my case the voltage had dropped to 1.09v.

Using a paperclip I was able to push the little battery out and then using a small set of needle nosed pliers I replaced it. Make sure you mind which side is up and down (the + side is down in the photo to the right).

When you put the toner cartridge back into the printer you will have to turn the power off and back on and then the printer should "see" the cartridge again.

Click on any of the images to enlarge them.