Hi @joub ,
Use a strong light and a magnifying glass to inspect that the micro USB charge port enclosure is not blocked with lint or debris which may prevent a good electrical connection. Also check that all the pins are there and that they are straight and parallel with each other and not bent or broken etc. If there is any debris in the port enclosure, ''do not'' use a metal pin or probe to try and get it out. Try using a vacuum cleaner and see if it will come out or if that doesn’t work, use a sharpened wooden toothpick to ''gently'' prise out any debris.
If the charge port seems clear and OK the speaker will need to be opened and checked. When the speaker has been opened, check that the micro USB charge port is secure on the circuit board and not loose etc. If it appears to be OK then perhaps the battery has failed and needs replacing.
I cannot find a teardown of your model speaker but here’s a [https://www.youtube.com/watch?v=I2j3dLM13u0|video] that shows how to open a UE Roll speaker so hopefully it may be similar and be of some help.
Replacement batteries are available online. [https://www.amazon.com/Replacement-Battery-LOGITECH-WS600BL-WS600VI/dp/B07KSQ47GX|This] is an example only to show what it looks like and the cost of the battery. Just search online for ''UE Roll 2 battery'' to find suppliers that suit you.