This symbol flashing in the right hand side of the display indicates that the boiler is due a service, it can be reset in the boilers parameters as long as the boilers maintenance is up to date.
If the symbol is not flashing it will usually have a number next to it and this is the number of months left until a service is due.
It is not a fault and the boiler will keep working during with this in the display.
Refer to adapt for guidance.