Ring doorbell pro can't turn on

Hello, need some help. My wired ring doorbell had been working for about 3 years, now stopped working, basically it went offline and cannot turn on. I checked transformer voltage and its output is more than 19V, then checked the voltage in internal chime which is about 0.6 to 0.8 (this is also where Pro Power Kit is connected), then I opened ring doorbell and the voltage it received is about 18.5V. So it's my understanding that the transformer voltage is good, ring receive expected power. Do you see any issues with these findings? I also tried 1) removed Pro Power Kit, retest, same thing. 2) I removed the 2 wires from ring doorbell and connect them shortly, my internal chime worked. I can not connect ring doorbell directly to transformer because it's quite far away and the wires are hidden in walls. Could anyone has experience give me some clues or ideas what else I should try? Or is there a way to tell if ring doorbell itself is dead? or the Pro Power Kit is malfunctioning (I am not sure if ring doorbell can work without it)? Appreciate any help!