Hello, I have a very concerning issue with my Mac at the moment. It is a MacBook Pro 2015 13". Yesterday, I shut macOS down properly. Today I tried to power on the machine, and the power on chime sound played completely one time, and from there on looped the second half of the sound infinitely at about 1 repetition every 3 seconds and the display backlight was on. I already tried resetting the SMC, which changed nothing, tried resetting the PRAM which started looping the chime and finally I held down the option key to show the boot option, but that also hangs. As the hang occurs before the OS is even started, I don't think it is related to the installed software. what should I do now? The MacBook was bought in Switzerland as far as I know and I live in Germany. Is there anything I could try or should I consider taking it to an AASP?