Ruuvi image -> Espruino image

I got to update my ruuvitag via Ruuvi Station.
But now I can not install Espruino via nRF Toolbox.
It says HW vesion check failed.
How do I proceed?

Hello,

Espruino is not compatible with Ruuvi FW 3.X. You need to have a Ruuvi Devkit to downgrade the firmware back to 2.X and then install Espruino.

It should be noted that newer RuuviTags with SHTC3, DPS310 and TMP117 sensors might not be supported by Espruino at all.

Why have you blocked the downgrade to 2.x?
I have none of the newer ones.
It’s a little too expensive for a devkit for one ruuvi.

Espruino and Ruuvi FW 2.X run on top of Nordic SDK 12.3.
Ruuvi FW 3.x works with Nordic SDK 15.3, which have updated software radio and bootloader.

Updating from 12.3->15.3 is safe, but downgrade through Bluetooth may lead to bricking RuuviTags, which is why the bootloader won’t allow downgrade.