While diving into R/C hobby, I learned that all the batteries within one technology are pretty much the same.

Like all Li-Ion batteries have nominal voltage about 3.6V-3.7V, and full charge at about 4.25V, depending on how risky you are today (yes, there are some minor variations in rated voltages, but not like 10x). Just because chemistry. For lower current (heat losses) you just connect the cells in series, so you got multiplies 2x, 3x, ... of the same voltages (but never fractional, like 1.5x). They typically have more wires to balance the charges between the cells (so the total wires count is #cells+1).

There are also "protected" batteries, which means there's an electronic chip that protects battery from over/under charging, but authors' doesn't seem to have that. It's just a regular unprotected 1-cell Li-Ion cell, and the device provides the protection.

That means author could as well connect to any battery of 3.5V -- 4.2V, not going through the hoops of looking for their particular reader, as long as it's thin enough to fit. Smaller batteries would just have less charge.

PS: I would double-check it's really unprotected tho.

I replaced the screen on my Kobo Clara hd recently after it broke; by far the hardest part was removing the old screen from the glue holding it on to the metal plate. Apparently newer models are much easier to repair.

Also, while you have it open (in fact, go and open it just to do this!), replace the internal SD card; they have a tendency to fail; my ereader had been getting very annoying with lag and random reboots until I did this, now runs like a dream. You'll need to copy your old sd card across or find an image somewhere (they exist on some forums) if it's too far gone (I got the bulk of my using DD rescue but there was a _lot_ of errors)

This is actually terrifying.

Ereaders tend to be fairly unique. If my Kobo Forma dies, there's no other Kobo I can replace it with (in terms of size). I don't want to change brands and deal with yet another OS.

That is pretty cool and looks easy enough to do. I have never seen batteries like that original one seems to be, it looks quite malleable? Is that normal for it? Has anyone seen batteries like that in other products? Most of the other things I did replacement have been “harder” batteries.

This gives me assurance that when my libra 2 eventually fails that I’ll be able to repair it instead of buying a new one. I love my ereader and have no need to replace it. I just loaded koreader onto it for the first time after 2-3 years of use stock. Feels like a new device! But stock was totally fine too. I just wanted OPDS and kosync.

Very cool. Would like to do this with my Kobo Clara

The H2O model is water tight. Is there anything about seal on the outer shell to take care of?