Hello good morning every body i have a problem with my asus eeePC

when I try to start it I load the system and after it shows me a black screen tchecking battery test! I come into troubleshooting mode and I selected the root to the other options available in the shell does not work and I do not know how to use the root user in troubleshooting mode accessible from the start of live travel ! who could help me it is urgent! thank you in advance