Hi , sounds like the boiler isn't re ognising the flame or its overheating
Hi what's the make of the boiler?
Check for overheating . does the boiler get up to heat , then cut out?. This could indicate week pump/sludged heat exchanger . ?
Also , check for clear condensate trap. If the boiler sounds like it keeps trying to restart
Then it could be the flame detection probe
Are you with the boiler now?
Hi , if satisfied with your answer , can you please give a positive rating , thank you