Trust Primo Touch Wireless Earphones

Original price: 29.99 EU, though now they seem to be available starting from ~19 EU.

This particular item was not charging at all. Box is held together by few latches and is easy to open.

Damaged IC: IP5305. Available on aliexpress, although I had second box from other set where one of the earphones was damaged/quiet, so I've just swapped it.

This cell looks swollen, although it does not seem to be the case and it accepted charging when I've detached it from the circuit.

KMT-F1 V1.4 2020-04-16

Four LEDs indicating charge level. Pogo pins charging earphones.

Location of the magnets.

After swapping charging box I've got working set. 
From the quick test - sound quality seems to be quite fine and earphones seem lightweight and convenient.

Measured time of music playback from phone with BT 4.0 at maximum volume: 1h50m (with few extra minutes left after power cycling). As maximum volume is pretty decent, using it for nearly two hours would be tiring/painful - in typical use these earphones would work longer.

It seems that these earphones enter pairing mode by default when there is no connection.

Excerpts from FAQ:

1. Turn off the Bluetooth connection on your connected devices (Bluetooth phone, tablet, etc.)
2. Take the Trust Primo Touch Earphones (both earbuds) from the charging case. Make sure they do not connect with any Bluetooth device such as your phone.
3. Double press only the right earbud, now the right earbud will be searching for the (so-called slave) left earbud.
4. The earbuds should be connected to each other within 30 seconds. The earbuds will prompt with a confirmation sound. After this you can connect your Trust Primo Touch Earphones to your phone as explained in the user guide.

If the earbuds won't link together, probably both earbuds are set as 'master', we advise the following to resolve this:

- Ensure that the earbuds are unpaired from all devices (phones, tablets, laptops, etc.), they were previously paired to.
- Put both earbuds back in the charging case.
- When the case has been fully charged, take one earbud (left) out of the case and connect it to your device.
- When this earbud has been succesfully paired to the device, take the other earbud (right) from the case so it will connect automatically to the other earbud and synchronise (wait for it to flash blue, not red / blue).
- Then both earbuds are linked and should work in stereo.