How to enter to u-boot enviroment ?

[BlackS]

Hi all,
sorry for a kiddy queston but it the first time when I'm using Armbian.

I need to enter to u-boot menu/enviroment/shell and I can't 
I try to press any button when I'm rebooting but nothing happened and i've just have a booted system 

I have only UART to my system. 

 

In other devices I have some time to press any key to enter to u-boot shell but there I don't have time. 
U-boot exec bootcmd immediately

I need to enter to u-boot shell and reconfigure some env for my work.

 

I use Armbian 25.8.2 noble

 

Edited 2 hours ago by BlackS

[Werner]

I'm not sure bit IIRC there should be a 1 second delay which would allow interaction but again, not sure...