MikroTik

Hi... i have a trouble with my 450. power LED blinking
can't booting, beeping but bit volume and eht LED blinking too but dim. whats wrong?
this preview video
https://streamable.com/hizva5

Well used RB450 routers had power supply electrolytic capacitors that went faulty. They could often be identified by bulging tops and/or bottoms on the effected capacitors.

Agree, years ago I fixed many RB450 (and RB4xx in general) by just replacing all caps. Even if they don't look bulging, it's worth a try.
Weird flashing LEDs or "dim" looking LEDs are typical symptoms.
Yours seems to be in a reset-loop, maybe because power supply just can't deliver required power for it to boot (thx to the bad caps), so voltage drops, that triggers a reset and everything repeats..

Agree, years ago I fixed many RB450 (and RB4xx in general) by just replacing all caps. Even if they don't look bulging, it's worth a try.
Weird flashing LEDs or "dim" looking LEDs are typical symptoms.
Yours seems to be in a reset-loop, maybe because power supply just can't deliver required power for it to boot (thx to the bad caps), so voltage drops, that triggers a reset and everything repeats..

so... what should i do? replacing all caps? btw caps like normally without bulging

You can also check all power rails with multimeter if they are stable or even better with a scope (transients can be too short for a multimeter).
Usually if power supply was faulty, it would not even try to boot (if one of the voltage is just missing, CPU will do nothing at all).
Instead of removing all caps, it's also possible to quickly solder bigger caps in parallel for a test if it helps or not.
But as always, nothing is guaranteed, it may be caps or it may be something else.
But I suppose you have already tried all other options like loading backup booter and there is nothing on the rs232 console either, so it's not a classic bootloop.

Short circuit