Some of the Bosch boilers are sensitive to power interruptions.
Try turning the main power off at the switch (switch-fuse), not on the front of the boiler, leave it off for a few seconds then switch back on again.
You may have to press the boiler's on/off power switch to switch it back on. When it is on the main indicator light will be on. There is a second smaller indicator with a flame symbol next to it which indicates when the gas burner is operating.
If the main light continue to flash, expecially after presseing the reset buttons, then there is a fault.
Paul, January 2009