I messed up Bottom round roast

For future reference, I follow the Cooks Illustrated recipe.
Heavily salt the roast, wrap in plastic and refrigerate for 24 hours (I lard it with garlic).
Unwrap, place into 225 deg oven with temperature probe, cook to 115 deg, turn off oven leave roast in oven until 125 deg for med rare

You could also slice it thinly, toss the slices with a nice mustardy vinaigrette (and let those slices sit in the vinaigrette for a little while ) and then serve them over a big pile of mixed lettuces that you've tossed with a touch of the same dressing. Throw on a few freshly baked or pan fried croutons, and one or two cooked beets cut in cubes, or some marinated artichoke hearts, or whatever else you like on salads. There, dinner! ;o)

My mother used to make barbecued beef sandwiches out of leftover roast beef. She’d put it in a slow cooker (you can do this in low on the stove top or in a low oven) with her favorite barbecue sauce for a long time (think low and slow) until the beef was falling apart. Serve it on rolls. With cole slaw. Now I want some!

Not sure, but guessing - as the cut is quite lean - that it may have been cooked without enough added fat or moisture.
It can probably be saved and used for sandwiches or soup.
Perhaps cook it in a broth laced with good-flavored fat. Once done, remove meat from broth, then slice for sandwiches or cut in large dice for soups or salads.
Save the beef broth for other uses.
For more help, see article in link.
https://tastessence.com/how-to-cook-bottom-round-roast