I was updating the router, but it took a long time to turn off and it became a brick. I connected it by serial communication, and the following log only stopped. What should I do?
U-Boot 1.1.4 (Mar 1 2015 - 22:07:55)
ap135 - Scorpion 1.0
DRAM: 4 MB
Please provide more detail about your situation. For example, router name/model, which firmware image you flashed and how did you flash it.
Is this the entire bootlog? There should be more than that. The router should try to load the firmware and if it fails it will reboot. Are you experiencing short reboots? What does the router do with its LEDs, any strange behavior?
From the looks of this, there's maybe only 4mb of RAM which seems really low for a router to run OpenWrt and it will be impossible with this one.
my router is DW02-412H and i use this firmware: https://manatails.net/blog/2018/01/kt-dw02-412h-커스텀-펌웨어-적용하기/
Actual ram and nand is 128mb. Also, the LED does not turn on, and only the log is shown in the serial. And stop. The reboot button works.
From Google Translate of that page, the first two lines are
NOTICE: This operation overwrites the firmware of the router. If it is wrong, the router may become brick.
It is also impossible to confirm that there is a model with the same internal structure as DW02-412H. Please note that the images below are not compatible with the current router.
As it seems what you flashed may be based on OpenWrt, it is not OpenWrt, so contacting the author of that page would be a wise decision.