Do you have an E18-2G4U04B to use as a zigbee coordinator with Home Assistant? Its a nice good-looking USB type of CC2531, increased range even, BUT… its really hard to flash! Why? because of the connectors.
Even if you have a CC debugger, you will need to micro-soldering 5 cables (or at least, is the official info), and after flashing with zigbee2mqtt, de-soldering again! 
Just in case you want to see the official page, you maybe need soldering with a lot of precision:
Well, there’s another way to do it, fast and without soldering at all
You’ll need:
1 CC2531 ZigBee USB Wireless Module, Model E18-2G4U04B (obviously)
1 CC Debugger (texas instruments)
5 dupont male to female cables (it’s easier if you leave them together)
First, bend a little bit the male end of the dupont cables to make them converge
Then, connect the dupont cables to the CC debugger on the female side, like in the diagram of the official page (above):
1 GND (green, in this example)
2 Target voltage sense (brown)
3 DC or debug clock (orange)
4 DD or debug data (red)
7 Reset (yellow)
It should look like this:
and connect them in this order (from antena to USB): green, yellow, orange, red, brown.
Sorry, I borrowed the E18-2G4U04B to a friend, so i use a screen image 
You actually only need to hold them for 30 seconds, if you have the firmware and the software ready to flash, like they describe in the zigbee2mqtt page (https://www.zigbee2mqtt.io/information/flashing_the_cc2531.html).
And that’s it, you can have an E18-2G4U04B flashed and ready for Home Assistant, just bending 5 dupont cables and no soldering at all 