Kobo Aura H2O Battery Replacement and Disassembly Guide

A few days ago, I published an article on replacing the battery in eBook readers without knowing that I would soon be dealing with the issue myself. When I tried to use my Kobo Aura H2O yesterday, it wouldn’t turn on: the screen just instructed me to plug the device in to charge. When I did, the eReader turned on immediately, but instead of showing the charging status correctly, it claimed that the battery was already full. Once I disconnected the USB cable, the device shut off immediately, and the last displayed screen froze in place.

Clearly, there was a power supply issue. Given that I had frozen the Aura H2O for an experiment, I suspected it was a resulting damage. The eReader functioned perfectly fine for six months after the test, and then suddenly stopped working.

As I didn’t expect a consequential damage to be covered by warranty, I decided not to send the device to Kobo Service but to open it myself to see if I could fix the issue independently.

Procedure

First, I gently widened the gap between the front frame and the back using my fingernails, then used a plectrum to separate the two halves of the case. Unlike most other eBook readers, these parts are not simply snapped together but are also securely glued due to waterproofing.

First, you have to carefully loosen the sealant piece by piece

So, I gently removed the adhesive with the makeshift plastic tool centimeter by centimeter—which worked quite well. Community member “Frostschutz” used a scalpel for this purpose, which is probably an even better choice. However, one should be careful (and work with a delicate touch) so as not to damage the internal components of the frame or the display.

After working my way around, I was able to remove the front frame with a little levering. It’s also important to note that there is adhesive around the display as well. Still, it’s sufficient to carefully lift the frame out.

Front removed

With that done, the electronics are only held in place on the back with four small Phillips screws. Once these are unscrewed, you can remove the mainboard, along with the battery and display from the case, holding the bare Kobo Aura H2O in your hands.

Electronics outside the case

Replaceable Internal MicroSD Card

At this point, the H2O does not differ much from other eBook readers. The usual components are in place and resemble the known configurations of previous Kobo models and those from other manufacturers.

The Aura H2O uses a Freescale i.MX507 CPU (ARM Cortex-A8) and Nanya memory NT6TL128M32AQ-G1. The Neonode zForce is used as the touchscreen controller, which is no surprise given the infrared technology in use.

Mainboard of the Kobo Aura H2O, visible corrosion marks at the bottom right near the serial interface and screws

Like other Kobo models, the H2O also has an internal MicroSD card with a capacity of 4 GB. You can clone the contents of the memory card and replace it with a larger one if desired. This worked perfectly with the previous models.

The mainboard and display are held together with another six screws. Once you disconnect the two flex cables, you can separate these components as well. This offers a good view of the 54 infrared sensors located around the back of the mainboard (see image).

Infrared sensors on the back of the mainboard

The battery capacity is 1,500 mAh, with the same battery (PR-285083; 3.7V, Li-Ion) used as in the Kobo Aura and Tolino Vision (1 & 2). This strengthens the assumption that most eReaders come from various reference designs by E-Ink Holdings and are only slightly modified by the providers.

Consequential Damage from Freezing

In any case, after disassembly, my Kobo Aura H2O displayed corroded areas, suggesting that condensation had built up inside during the freezing process. If the lower flap for charging is opened, then warmer (moist) air can also flow into the housing. During freezing, moisture settles on the components.

It’s wise not to replicate my little freezing experiment!

Completely disassembled

The pin connector to the battery was also superficially corroded. Unfortunately, cleaning the connector and plug did not resolve the issue—the Aura H2O couldn’t be used without an external power source. To narrow down the problem further, I first opened a Kobo Glo (the back cover comes off with a few simple steps) and used the battery in it for testing.

Because the H2O could be turned on without a power cord in this way, it was clear: the battery of the device was damaged, presumably due to prolonged exposure to temperatures well below 0 degrees. A Kobo Aura, which also uses the same 1,500 mAh battery, had to act as a donor.

Extracting the battery was a bit tricky because the double-sided adhesive was extremely strong. However, carefully using an old credit card to loosen the glue got the job done with a bit of patience.

The adhesive ensures waterproofing. Once the Aura H2O has been opened, it is no longer waterproof.

Once the new battery was installed and secured, the reassembly of the eReader took place in reverse order. Now everything works as it should—though no longer waterproof. After such an operation and the removal of the frame adhesive, the case’s waterproof seal is now compromised, meaning the IP certification is certainly no longer met. If you decide to open the Kobo Aura H2O yourself (for instance, to swap the internal memory card), you should avoid contact with water in the future.