@arboltioloco have you tried the solution in this topic?
I also had problems installing luci on the RE200 (v4)
What I did was flashing it with;
http://downloads.openwrt.org/snapshots/targets/ramips/mt76x8/openwrt-ramips-mt76x8-tplink_re200-v4-squashfs-factory.bin
and then installing via the web browser this one;
http://downloads.openwrt.org/snapshots/targets/ramips/mt76x8/openwrt-ramips-mt76x8-tplink_re200-v4-squashfs-sysupgrade.bin
Then it won't reset after a restart, so you can use this topic.
Good luck 