Quick update : it fixed itself ! I had the lighthouses unplugged for a few days. Today I plugged them back. No firmware update showing. Made a system report : bluetooth driver correct version. Turn off steam VR and TADAAAA turn off automatically. Hope yours get fixed soon too.
Base Station Firmware Update Do not downgrade firmware versions on basestations.
Connect the base station over USB to a USB 2 port in your computer. A micro-usb cable is required. Make sure that the cable is fully inserted in the plug of the base station. The housing might prevent the needed close connection Power on while pushing the Mode button to get the drive "CRP DISABLD". This may require multiple attempts. Find the 'lighthouse_tx' firmware directory in your OpenVR Runtime directory. For example: C:\Program Files\Steam\SteamApps\common\SteamVR\tools\lighthouse\firmware\lighthouse_tx Select the appropriate file, suitable for your basestation model. For those with the development edition "Robin" basestations, use lighthouse_tx_robin.bin Delete the firmware.bin on the "CRP DISABLD" drive (you must do this, or the next step won't work) Drag the ".bin" file onto the drive (or, copy + paste) Power cycle the basestation to complete installation. USB is not required during reboot.
If you repeat the process, you will see firmware.bin with a fixed size and fixed timestamp. That's okay.