G'day gelun, welcome to GPS Power.

SP2720 has about 1.7GiB total usable internal memory i think. 672,100KB is way short of the 1.9GB you're trying to upload and even if you clear everything else off it's still not going to fit on there if i'm correct in recalling 1.7GiB and anyway maps are flashed to 'regions' which also have limited size which can't be exceeded regardless: Primary map to region 49 [hex 31] and supplementary map to region 10 [hex 0A], they seem to share flash memory space and i think it's a maximum of 1.1GiB if i recall correctly. Also an oem map can be flashed to region 50 [really tiny only 1MiB]. So, you'll need to reduce the size of the map to less than 1.1GiB even if you remove any other detail map.