I got ZTE ZXHN H369A, there is no much information about it on Openwrt or other sources except some information on Tech Info Depot, You can check this link for basic information, but it does not have info about CPU, WLAN / Eth Chips, RAM, Flash, etc.
So, I opened the case and her below the additional information I have so far:
Uh, another Broadcom-based device...
According to this (i don't know if this page is up-to-date) , this SoC ist still not supported in OpenWrt.
And considering the lack of open source drivers for Broadcom chips, i don't know if it's a good idea to spend too much time with devices like these...
If i remember right, i think i've seen something like this some years ago on a Broadcom-based set-top-box.
My guess is, they just disabled the normal boot messages or send them straight to /dev/nul.
Just found this one.
It seems, that's the typical Broadcom boot log
I was missing the part where there were additional boot messages on other devices, an none on this one...
Either a "security" measure (to secure their intellectual property?) or just "You do not need to know this".
That is also my guess, especially the same problem happens on ZXHN H368N router I have.
In the beginning; I thought it was a serial-TTL cable issue, but when I changed the cable, the problem still there. So it is not a cable issue. I guess they made something with boot-loader security.
The boot-loader is CFE (I think) not U-Boot!
Now I am sure it is CFE boot-loader. What I did is I turned off the router then pressed Reset button at start-up for 6 seconds. the router has very tiny webserver in this case (micro_httpd), with telnet to the router on port 80 I got the following