How much would it be to diagnose a problem?
I got my hdmi port repaired but now it's blinking red and I don't know what's wrong with it.
You don't need it diagnosed...I can tell you what's wrong just based on the info you gave: whoever fixed it, didn't fix it correctly. Most likely they did not solder the 19 small pins on correctly. If they are a good business they will fix it again for free (assuming that the port hasn't been abused or anything). If they refuse then you'll need to have it fixed again.