Help I bricked my device

I am so foolish i run opkg install busybox. After that my modem won't boot, the power led only light up. And my pc only detect ethernet for a few seconds on boot, then it disconnect. How to fix this? I have full mtd backup of the firmware partition can i use it?

if you use tp-link or azuz you can run your device in a recovery mode and load original image via tftp i guess.
if you use xiaomi it's over.

my device is ZLT S12

This device does not appear to be supported by OpenWrt (official). You may need to contact the vendor for help.

yeah. It uses a modified openwrt snapshot though.

DISTRIB_TAINTS='no-all busybox'

How was it installed in the 1st place?

It comes on the box

Modified is the key word. Modifications mean that it is not official, and therefore may work differently than would be expected from the official versions. That is why you need to ask the people who provided that version for help.

Ah, thought you installed it yourself.

Then you should follow @psherman's advice.