Yet to be discouraged by poorly attended gigs or a string of rejection

[Vladv1]

"At least the existence of Metal Massacre gave the nascent Metallica line-up impetus. Moreover, it demonstrated something to Lars and Jamesthey had not known before: that they were actually good. It was as if the fact that they didn’t yet exist outside the fevered imaginations of Ulrich and Hetfield had enabled them somehow to be more than the meagre sum of their parts. Yet to be discouraged by poorly attended gigs or a string of rejection slips from disinterested music-biz figures, they just blast it out, as sure-footed as two guys virtually miming in front of their bedroom mirror can be. Three weeks after the release of Metal Massacre, the band thought they had really cracked it when they went in to an eight-track studio in Tustin called Chateau East, where they recorded what they were convinced would actually become their first stand-alone release, following another typically brusque Lars Ulrich challenge to a more established local ndependent label owner. Unlike Brian Slagel, though, the owner was a punk aficionado – a genre still then diametrically opposed to heavy metal – and this time Lars’ bluff appeared to backfire".
Mick Wall "Enter night"

Could you please interpret the bolded part in other words, I get the individual words but can't get a coherent meaning.

 

[emsr2d2]

They had not yet been discouraged by gigs with very few people in the audience or by a series of music business executives deciding they weren't interested in signing the band to their label. Even though those things had happened, they remained optimistic.