After flashing the Spirit Pro with version 3.3.3 everything works very well. I can program it completely without any problems and the servos receive all orders from the spirit. As soon as I disconnect the batteries and reconnect them the Spirit Pro does not work anymore and blinks constantly in red.
I repeated the experiment several times and each time I arrive at the same result: the Spirit Pro doesn't work anymore.
I found no explanation for this problem.

Hello,

please send me serial number of the unit to private message.
The problem happened right before the problem appeared for the first time in the memory of the unit and could be caused for example by unstable connection between software and unit.
However it is not a problem and the unit can be fixed easily by flashing special firmware which will recover lost memory. Then everything will work fine again.

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Spirit System developer

I sent the serial number as requested to solve this problem. Thanks

My problem was solved with responsiveness and skill.
At Spirit System, support is highly reliable. You can trust them absolutely.
Thanks for everything.