Hi and welcome to the forum
The phone powers from the battery so using just the USB will not work.
Cleaning and removing the bottom module are options, you don’t have to do that.
If the phone was bought less than two years ago you can use the warranty.
Where did you get the info you quote?
- The red light only comes on when the battery is inserted and low
- If the battery is dead, check it hasn’t bulged, then clearly it may not work and has a significantly increased risk of damage to the phone and self igniting.
- The USB port can become dirty, tarnished connector or fluff.
- The pins could be damaged
- the module may have failed.
You can look all these issues up by searching this forum.
Sending off to Fairphone means a) you will have to wait to see their diagnostic report and b) who knows what they will or will not find. So a DIY is often a quicker and maybe cheaper option if you have no warranty
Links to follow . . .
For a breakdown which does not void the warranty do not go past Step 7 in the following
If you are out of warranty you can look at the following
Effectively you can remove all the modules without voiding the warranty but if you dismantle a module the warranty is then invalid