RT5350F-OLinuXino-EVB doesn't always boot

[zgyarmati]

I have an issue with my RT5350F-OLinuXino-EVB: most of the time when i switch it on it doesn't boot (in terms of not sending anything on the debug serial port, not even u-boot messages). Sometimes i have to reconnect the power 4-5 times before it boots up. I tried with different 5V power supplies, but i got the same behavior...
Does anybody else experienced the same problem? How to debug such an issue?