I try to disconnect from work and social media as much as possible over the summer but like any educator I get bursts of inspiration even on vacation. A long time ago I would collect old electronics, toys and computers for students to dissect. It's pretty satisfying to see kids tearing down devices using hand tools. Some would go to town destructively while others would methodically organize screws or parts. Most kids wanted to diagnose faults and/or combine parts to create frankenstein machines.
I have written previously about the advantages of understanding how things work by taking them apart. Destructive testing and reverse engineering are fantastic skillsets for curious makers that I try my best to foster in my spaces.
Unfortunately, some devices are designed to non-repairable. Companies may wish to protect intellectual property, save money by not supporting repair divisions, encourage planned obsolescence or maintain market capitalization by forcing participation in one ecosystem. Look over to iFixIt for a nice summary of Right to Repair.
This issue came up over summer when my electric toothbrush started acting erratically. It's an unnerving feeling when you get woken up at 3am by a strange buzzing from inside the house. Thankfully this was my second-go-round in dealing with faulty toothbrushes so I clued into the location pretty quick.
There is already quite the library of resources online interpreting error codes and beeps, teardown steps, and suggested fixes. Most suggestions seem to be replacing the low-cycle factory battery. What I can offer is a few tips that saved me a bit of the time the second time around.
First, opening the devices and removing the board is probably the hardest part. For my Oral-B brush I found using channel lock pliers with a cloth wrapped around the base worked well since the base extended up the sides a bit. I also used the charging base once but I wouldn't really recommend it since it doesn't offer much friction fitting and there's the chance you'll have a broken charger and toothbrush.
My newer Philips brush had base plate that was flush with the bottom of the case making it impossible to use a gripping appliance. I found screwing a bolt with coarse threads into the bottom then pulling it straight out with pliers worked well. The first time around I wrapped some soft tissue around the threads to reduce the tapping in the soft plastic base. You may have to find a bolt width that works for your model, I think mine was around 1/4" or 5/16".
Take care to not break any locking tabs when you slide the board out. The Oral-B board was more difficult to take since you need to finesse motor threads and battery tabs out of the way. Once removed, liberally apply 99% isopropyl alcohol to degrease and expel any moisture. Inspect for any other kind of residue and corrosion. I was lucky that mine didn't have any physical damage, though there was a lot of residue and it was clear water had infiltrated the case.
Removing the batteries was straightforward, just take care to avoiding nicking any wires and be sure to note polarity and tab orientation. I was able to replace my Oral-B with a standard AA NiMH Eneloop but my Philips used a LC18650 3.7v li-ion. If you're soldering tabs onto the batteries make sure to use a wide solder tip to reduce the time you're applying heat. I find the negative terminal harder to solder because of the larger surface area.
