I had a similar issue were I flashed philz recovery and it wasn't the loki'd zip.I to had the triangle of death with unauthorized ATT msg, I tried three times to boot into recovery and the last time I tried it went to (pic posted)and from there I pushed down for restart phone.it booted up like a regular reboot and was OK.
Also after it booted I lost custom recovery, so like I did the first time I achieved recovery I flashed with ROM manager clicking the T-Mobile S4 when prompted. Note : only use ROM manager to flash recovery.now use recovery to flash a auto Loki recovery. Hit thanks if I helped
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