LTM 1600 does not boot, stuck on "Press <esc>( for Command Menu...</esc>

After power on LTM 1600 the booting process stops at

--- Press ( for Command Menu, or for Host console.

: "C102"

When I hit Enter, nothing happens Sometimes ( works and I can see AOM Command Menu and I can setup AOM network and then SSH.

Why this system does not boot? What is the next step to figure out what is wrong?

Thank you