Users claim that the ANC is much worse after the official firmware upgrade to 4.1.1. A firmware downgrade is possible to 2.0 by tricking the Sony Headphone Connect Android application to update the firmware for the headphones from a custom server ran on the local network.

The following zip file:

• sony-wh-1000xm3-firmware-downgrade.zip

contains two python scripts:

• sony-WH-1000XM3-downgrade-2.0-MDRID291600.py - for international headphones,
• sony-WH-1000XM3-downgrade-2.0-MDRID291601.py - for Japan/EU headphones

with instructions at the top on how to downgrade the firmware.

The version of the Headphones Connect application that was used to perform the downgrades can be downloadeded locally:

• com.sony.songpal.mdr_4.1.0-41000_minapi21_armeabi_armeabi-v7a_nodpi_apkmirror.com.apk

The scripts contain a built in HTTP server that Android is made to connect to from the Headphones Connect application with the proxy settings pointing to the machine running the scripts. Once connected, the scripts will intercept the Headphones Connect requests to the Sony update server and then upload the payload (the scripts have the 2.0 firmware inside as a Base64 encoded string, hence the size).

The downgrade scripts are attributed to FormalDetail5.

It may happen that the WH-1000MX3 Sony headphone battery is sufficiently depleted such that the headphones do not charge the battery even after letting the battery recharge for a long time. Fortunately, the WH-1000MX3 is easily disassembled with the battery being contained underneath the cap of the right headphone. The pads can be lifted with a long screwdriver and popped off in order to reveal 4 screws underneath that have to be removed for the cap to be opened and the battery revealed.

Once the screws are removed the cap on the other side will pop off easily and reveal a LiPo battery on top. The LiPo battery is a standard 3.7V battery with what looks to be a thermal sensor on top and with two leads that connect to the headphone PCB. The battery connector can easily be pried off with a screwdriver and removed from the socket.

Two sharp pins can be inserted into the battery connector and then using alligator clips, the battery can be connected to a standard LiPo battery charger. A full discharge-charge cycle can be programmed on the battery charger in order to get the level of the battery up and allow the MX3 to recharge the battery again.

The charger used was an iMaX-like clone that is a well-known battery charger able to recharge different types of batteries. The very same technique of jumpstarting a battery when a battery is too depleted to recharge can be used for the Roomba Robot.

On a side-note, there are reports mentioning customers sending the headphones in for repairs and the official narrative in some cases says claims that the headphones have been left to charge for too long. However, the battery used by the MX3 is a LiPo battery without memory compared to NiCd batteries such that charging the headphones all the time is, in fact, preferred.