help update nuvi 2559lm maps

Hi Everyone

i need help, please i have nuvi 2559lm with Western Europe NTU it was 2016 but i updated by garmin express to 2019.20 which looks okey, but i want to add Eastern Europe NTU 2019.20 cos i am planning to go to my country , so i download Eastern Europe NTU 2019.20 unlocked img and i placed in ./system/maps folder , but when ever i start my navigation it says cannot unlock maps)

i start reading and find out that my system version is protected which is 8.80 and before update if i remember correctly i had 8.30 which most likely would work, so now i stuck i can not make work Eastern Europe NTU 2019.20 on my nuvi,

i know i need to if i understand correctly downgrade my version to lover like 8.70 and patch it , but there is no much info and its a confusing

can someone help me and redirect to the right post? please

so far what i done i find website where i can download lover sw version [Please Register or Login to download file] i download 8.70 and i remove original GUPDATE from my nuvi and replaced with an older sw but when i start my nuvi i am not getting any message to downgrade .

i stuck please if anyone could help me i would really appreciate it

regards
gugutm

there is no need to downgrade but to patch your new firmware