Here's what I found. I always suspect the power supply first.
Source: https://chicagodist.com/blogs/news/raspberry-pi-troubleshooting
Raspberry Pi 4 Troubleshooting
The Raspberry Pi 4 works differently than previous versions which means the blink patterns are also different and indicate different things. The boot up is more complex and has more features, so if it doesn’t find a valid start.elf file on the SD card it will blink the LED four times with an interval between the four blinks. Which means unlike the older boards it won’t mean that the SD card is booting, it means the code can’t find the SD Card at all.
The YouTube looks like four blinks of equal length to me.
Here's what I found. I always suspect the power supply first.
Source: https://chicagodist.com/blogs/news/raspberry-pi-troubleshooting
Raspberry Pi 4 Troubleshooting
The Raspberry Pi 4 works differently than previous versions which means the blink patterns are also different and indicate different things. The boot up is more complex and has more features, so if it doesn’t find a valid start.elf file on the SD card it will blink the LED four times with an interval between the four blinks. Which means unlike the older boards it won’t mean that the SD card is booting, it means the code can’t find the SD Card at all.
The YouTube looks like four blinks of equal length to me.