I am having a problem with my old laptop (GPU: Mobility Radeon HD 3470). I upgraded from Xubuntu 19.10 (where everything was working fine) to 20.04. Now, when I boot I get a black screen (before I login). I can boot using low graphics (not a viable option to keep using). I tried installing Proprietary drivers but I get an error: Detected X Server version 'XServer _64a' is not supported... Is there anything I can do?