1. Plug battery in while pressing the button. Release the button. Now press and hold, counting the LED blinks as you hold the button down. Release when you’ve counted enough blinks for your target time. One blink = 1 second. The max time is 250 seconds. Upon release of the button, the timer will save the DT time and go into idle mode.

2. Press and hold the button until the LED turns on solid red. Upon release it will start timing.

Be sure to test your rubber bands to make sure they cut reliably with your chosen battery. There’s in instruction about enabling high current using a solder drop. Do that, and be sure to remove any high current/voltage protection from your battery. In the case of the common 100mah lipos, there’s a protection circuit under the kapton tape at the contacts. Carefully remove the tape, unfold the board, and move the wire on the middle contact to the unused outside contact. This removes the protection circuit from operation and allows drawing full power, regardless of charge state, from the battery. Make sure you keep your batteries on storage charge (3.7V) when not in use. Fully charge them to 4.2V when flying and don’t ever launch on less than 3.8V.