That sounds odd.
What things do you have connected to the board? Some pins need to be in a certain state at boot-up otherwise it either won’t boot, or Wi-Fi wont be enabled (which could cause the device to appear dead if you’re running Blynk code and using Blynk.begin as that will block the execution of any other code).
GPIO 0, 2 and 15 are the pins to look out for, as devices connected to these pins could be pulling them up/down at boot time.
Read this for more info: