U-boot wrong font display

I'm up openwrt firmware for Tl-WDR3500 v1, but error 18005

I try up via serial (using CH341A board and PuTTY) and u-boot show strange characters until the Linux kernel booting

when the device boot complete, I can still login via root user (user:root, pass:sohoadmin) but unknow how to up the original firmware.
however, even though SSH is active, it can't be logged in as root

help me, thanks adv !

Check your settings for the COM port.

Normally, it should be 115200, 8, N, 1

Of course, I did set 115200 8N1 for COM and PuTTY, otherwise the linux kernel also does not display.
I think, maybe u-boot was locked by tp-link inc.
I installed LEDE on TL-WR941DN and it worked very well.

I adjusted the speed to 117000 then accessed u-boot and installed LEDE succesfully. I think, maybe the matter is CH341A board.
I am ordering another USB2TTL, CP2102 board, hope it will be better.
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