The IRS would prefer for you to NOT efile a return after mailing it ... doing so would put 2 returns into the system at the same time and can further delay the processing even longer ... so do NOT efile if you have already mailed in the return. If you mailed in the amended return prior to the original return being fully processed that will delay things also.
In normal times amended returns can take 4 months or more to process however with the covid shutdown add another 3 - 4 months to the normal processing times. All you can do is wait patiently and check the IRS site once a week until they open your envelope and process the return.
