Had a couple of issues with my Crux35. It’s fail safed in a couple of locations I really wouldn’t expect it, which made me go hmmm. I’m using TBS Nano Tx/Rx and that has never even blinked on any of half a dozen quads I have that set up on.
The last FS lead annoyingly to a fairly hefty crunch. I thought I’d dinged one of the motors as it wasn’t spinning up correctly. Turns out the motor is just fine (tested on another quad) - but I think the ESC / FC has sadly got some issues.
Plugged into BF and manually spinning up the (new) motor gets this behaviour…
Fails with a single beep. Second beep is when I return throttle slider to zero in BF.
So I’m wondering if this is just the latest symptom of a failing FC. Is £50 for a new one - but is actually in stock atm (mild surprise), but not great if this is what’s failed and there is the potential for the same thing to happen again.
Is it possibly a voltage spike? Have you got a decent sized cap on there?
As for just replacing the FC with the same type, a new one that’s exactly the same is more likely to have the same problem. I’d be tempted to buy a similar one from a more reputable manufacturer… though to be fair HappyModel are pretty good.
No msg that I saw - but I’m using DJI / Vista which gives a limited range of on screen info (it’s set with the hack to display msgs in the craft name field in the OSD but nothing showed up there… or not that I saw as I span into the floor!)
Interesting note re the cap - cheers for the heads up else I probably wouldn’t have looked.
Checked closely and… positive side has come adrift. doh.
So, I bought a new FC (same F411) … which is then a complete brain transplant. Actually went back together really sweetly. I backup all the settings in BF then flashed them to the new board. And for once, everything worked!
Will go out for a longer razz tomorrow. 
