SOLUTION
This may seem harsh, however, a person who genuinely wants to perform and has gotten the necessary training, but is still incapable of performing satisfactorily, will likely be frustrated his entire career. Finding a job he can do well is the solution.
The best solution may be to gently nudge the individual in a direction that better suits his/her capabilities. Look for opportunities within your organization that provide a better "fit" for this person's capabilities. If possible transfer this person to a job or role he/she can perform. If that fails, it may be necessary to terminate the individual. If termination is necessary do so with dignity, respecting the individual and encouraging him/her to pursue opportunities more in keeping with his/her skills.
Analyzing and Solving People Problems
Solution Explanation:
Sometimes the best solution is to gently nudge the individual in a direction that better suits his/her capabilities. Look for opportunities within your organization that provide a better "fit" for this person's capabilities. If possible transfer this person to a job or role he/she can perform. If that fails, it may be necessary to terminate the individual. If termination is necessary do so with dignity, respecting the individual and encouraging him/her to pursue opportunities more in keeping with his/her skills.