BBB doesn't work without SD-Card after update


I’m newbie in this stuff. I got my BBB couple days ago and ran it. Everything worked fine, but I couldn’t connect my BBB with internet, so I thought I should update my system. So I made everything, what I should to. Edited uEnv.txt etc. Pressed S2 Button long enough. So in 30-40 minutes I checked my BBB and it had Debian 9.1. I shut it down then booted without SD Card. But it didn’t start. USR 0 and 2 light up for couple seconds and after that no USR light at all. With SD Card it boots, but only with Read-Only System. What did I wrong? And what should I do to fix it? Thank you