Error installing mbn file on EC25

These are the steps I followed in installing the mbn file and I ran into a few errors.
While following the docx which was provided by Quectel support How to add MBN by command.pdf (388.8 KB) , on Step 4, Substep 4 I got an error. While running at+qflst="RAM:*" it says ERROR the first time, But when I run the same command again it says `OK.
then while loading the mbn file also I get an error “CME 421”.

I checked there is no mention of an ERROR Code 421 in Quectel datasheets

Hi there
I think you may have some mistake in step 6
You should send the mbn file via click the “Send file” button after you execute at+ qfupl= "RAM:mcfg sw.mbn’”,31956 command.
Then add MBN to module by command AT+QMBNCFG=“Add”,“RAM:mcfg_sw.mbn”.