It also exploded after lifting the second stage to its desired speed, plus performed a hot stage, plus reoriented for the back boost burn and re-ignited before it blew up. This was a phenomenally successful flight for the first stage.
Not sure where you got that impression from. The booster apparently worked flawlessly during ascent, with all 33 engines working until stage separation. Only 30s into the boostback burn, the AFTS triggered after several engines shut down prematurely. The second stage was deployed successfully, and completed most of its burn, before being lost only around half a minute before scheduled (sub)orbit insertion, around 3km/h short of the required velocity.