Happymodel ES900 Rx ELRS Boot Issue - Fix Using Manual Mode Flashing (NO LONGER REQUIRED)

UPDATE: Manual mode is no longer required as this is now the default behaviour in ExpressLRS 1.2.0. If you have an RX doing this, flash the newest version of ExpressLRS using standard mode in the configurator and your boot issue will be fixed.

My Happymodel ES900 Rx would get stuck booting which would prevent it from connecting to my Taranis QX7 radio or from flashing it. A quick replug would get it working but I wanted a better solution.

The developers for ExpressLRS already had identified the issue and had a solution. In short, an undersized voltage regulator prevents the ESP chip from completing its RF initializing as it pulls too much current. This results in the receiver freezing up. This work around essentially skips the RF initialization. A full description/explanation of the issue and solution can be found here:

For the manual options/build setting, a full description can be found here:

[hshpegel]

Hi, Many thanks for your informative video. I have the power regulator symptoms on my Happymodel 2.4 EP2 Rx. I tried your procedure with my 2.4 changes but configurator kept throwing errors when in manual mode. I turned to the Discord channel for help and was told that the fix for the PR is default so that it was not required to switch to manual mode to add it. Configurator in standard mode works without errors for me and PR issue now fixed. Not sure if this would be the same for your 900 system. In any case your video got me on the path to fix my problem and I appreciate your help.

[RakishRc]

I got a happymodel epw6 pwm elrs receiver and it had solid green light everytime power was supplied even when boot pads were not bridged.
I tried flashing using ftdi adapter and betaflight pass through but none worked. It doesn't even enter wifi mode.

[drankenwizard]

Thanks, for your video. Did you have some issues with heating? My receiver getting really hot. Wiring is good and it works fine. But the temperature is hot compared to other receivers that I had

[JP-qqkn]

Ive been trying to flash my Happymodel ep1 2.4ghz receivers for hours but keep getting error messages. I wish I never switched from frsky... Please help!!

[achefpv]

I flashed betafpv Rx it has a solid blue light but isn't talking to my tx already updated open tx and tx module

[rupinkachhadiya]

I tried multiple times to reconnect battery but the rx always solid red... What could be the problem