Briefly, I offered a repair service for these remotes on eBay. I fixed a dozen or so remotes using this methodology. I hope it serves you well.
There are 3 ribbed tabs on each long side of the remote and 1 ribbed tab on each of the short sides that fasten the top and bottom casings.
At the bottom of the device, insert a pry bar, angle it slightly, and slide it along the bottom of the device to free the first tab.
Repeat for the two long sides and finally the top short side.
Remove the top cover and free the battery terminals from the bottom casing. Remove the board from the bottom casing.
Each remote button works by completing a specific circuit when actuated with the button contact acting as a conductor of electricity. Over the years, oil and dirt may seep into the button contact, increasing the contact's resitance and making it more difficult to complete the circuit. In short, this necessitates harder button presses for the remote to work.
Lightly scrub the remote contacts and the adjacent circuit board side with rubbing alcohol, and test again to see if button tactileness has improved.
If not, the conductive coating on the button contacts may have worn away. There are a few options to restore conductivity. Gluing a small piece of aluminum foil to each afflicted button should work as long as the adhesive sticks. Alternatively, I have had success with a compound called keypad fix - affiliate link that is applied as a liquid and dries within the hour.
Typical range should be about 15'. Range can typically be extended by plugging in an FM antenna to your media center.
I suspect these range issues arise after the device is dropped, resulting in damage to two particular components near the top of the board.
At the top of the board is a cylndrical antenna wrapped with copper wire. Check that each end of the copper wire is securely soldered to the board. If either connection is slightly loose, use a soldering iron to fasten the connection(s).
Additionally, there is a 27.145 MHz crystall oscillator that is frequently faulty. Replacements can be found for a few dollars and install easily with a soldering iron (no polarity, so install in any orientation).
Attempt the fixes for minimum range.
Otherwise, check if the battery terminals are free of corrosion and securely fastened to the board; it shouldn't be a problem if the terminals can rotate somewhat. However, they should not freely pop out of the board. If this is the case, use a soldering iron to fasten the connection(s). When in doubt, use a multimeter to see if the device is getting power.
If all else fails, make sure you are using fresh batteries.
If all is lost, please consider using my affiliate link (at no extra cost) for a new remote: RC-9, RC-20, RC-25