Hi Adam,
thanks for your quick answer. I used a little different sequence. But i tried your way allways. But with the same result

. as you described, the serial number is shown, but the windows closed, without anythin else. I'd tried as you described, but it doesn't work.
I connected the timer to a USB Power supply, waited 30 Seconds, then disconnected. I'd switched on bt, an started the app. the timer was shown disconnected. i'd tap on disconnected ans the windows was shown. Teh iphone and the timer start to connect (I seen it in on the bold bt-symbol on the iphone). then i select the serial number in the windows. the loading symbol/starting cirlce appears after the serial number. But then, after 10 ot 15 seconds, the windows disappears/closes and nothing else happens.....

Is it possible to reset the timer?
Greedings
Wolfgang