HG553 - Can't update from 18.06 to 19.07

Hi everybody, I'm new to the forum but I'm using OpenWRT since 2018 and I love it.

I have a Huawei HG553 that I use as access point and other stuff. It runs very well with OpenWRT 18.06.6 but I can't get it to work with OpenWRT 19...

I tried compiling OpenWRT by myself, downloading it from the product page but nothing.

This is the description of my problem:

When I upload the firmware while pinging in background, I can see it responding to the ICMP after a minute and a half and the power LED start blinking. But then, after 20 seconds or so it stop responding to the pings and the power LED stays on without blinking. At this point I can't do anything but reboot.

When I reboot all the LEDs (Wi-Fi, ADSL and others) start blinking and I get only 5/10 responds to the ping. Then the LED keep blinking but I can’t do nothing.

So, something is clearly happening but I still can't do anything and the ping won’t respond.

The router is fine because it still works with 18.06 if I upload it. I also have another one like this and behave the same.

PS: I tried pinging at 192.168.1.x & 0.x and .1, .253 & .254 at the end. Obviously it don't work even in the browser.