re install

My first install did not go well. I had to reformat the drive a number of times and then when I eventually got a good flash drive it does not appear to have installed very well because many of the extra installs won’t work but return an error. Can I re install over the first one or is it necessary to reset the apple tv somehow and is there a way to avoid wiping out the films etc that are on there already.
Sorry - lots of stuff here! Thanks in advance