There are several reasons why your heat press might not open after the time has run down:
1. the gas springs are too cold. (below 10°C). After delivery in winter month this might be a problem right after you unpack the machine.
2. The press needs a certain minimum pressure to open. If the press does not open, set a higher pressure and try again.
3. In some very rare cases, the screws of the lever mechanism might be too tight. Loosen the screws a little bit and try again.