Substitute Kyle Hurst snared the winner in the 87th minute after Blues had twice been pegged back.
All the goals came after the break, with Amari Miller opening the scoring before the hosts levelled.
Then Remi Walker scored a spectacular 30-yarder, an effort worthy to decide any game.
But once again the National League North side equalised shortly afterwards until Blues finally saw them off.
Oriol Soldevila made his Blues debut and showed that he possesses nice technique, assured passing and decision-making.
Playing wide on the right, his game intelligence was also apparent as he dovetailed well with the vibrant Josh Williams, who again was filling in to very good effect at full-back.
Against opponents playing a back three and often dropping players in to form a disciplined barrier across the pitch, Blues had to be patient in the first-half.
In the seventh minute they worked the ball nicely to Miller, who was loitering at inside left.
He left fly from outside the area and his shot looped up of a challenging defender's leg and over the 'keeper and onto the top of the crossbar.
Blues had a big let off five minutes later when James Hardy planted a shot wide with the goal at his mercy, after a cross from the left eluded everyone.
From a flick by Josh Andrews, Fernandez shifted the ball out to Miller coming into the box and, after a touch, Telford's defence did well to get a double block on his attempt at goal.
In the final minute of the first period again Telford should have done better when Aaron Williams was played in on the right, but his fierce drive was saved off the chest of Aaron Clayton who got into the right position.
Blues started with gusto immediately after the break and were instantly rewarded.
Walker came deep to take the ball off the defence and moved it forward to Ryan Stirk.
Stirk looked up and clipped a sumptuous pass down the left channel, in the gap behind.
Miller hared onto it and before he was taken out by the 'keeper inside the angle of the area lofted a shot high and towards the goal, the ball taking one big bounce before it rippled the upper net (47 minutes).
Telford came back and might have equalised with a far post header at corner, but it was just off target.
And indeed they did, in the 54th minute, when Blues got themselves in a muddle wide on the left and conceded a throw.
Telford took it swiftly and although Stirk seemed to have done enough to stop an initial surge towards goal, the ball popped out and after Joe Redmond blocked one attempt Adam Walker smashed it past Clayton, hard and low, from just inside the area.
From the hour mark, and after Telford made a raft of substitutions, the contest really began to open up.
Miller's backheel invited Mitch Roberts to cross on the run and after the ball was missed by a defender Fernandez got an effort away at goal but it was well saved, Russ Griffiths flinging out his arm to parry high above his head.
From another swift attack Soldevila fed Andrews down the right, he cut back onto his left foot but fired over the crossbar.
Then, in the 72nd minute, Walker produced a moment of magic.
It came after a run by Hurst enabled Roberts to cross low into the box, which was hastily cleared out to Walker.
Setting and shaping himself, Walker then let rip with a zinging right-footer which flew in off the upright.
Blues were threatening to cut loose; Miller, now on the right after Hurst's introduction, had a shot turned just behind by a defender following Andrews' break from halfway.
Next Hurst waltzed inside, after taking a long diagonal pass by Walker, before seeing a low drive well grabbed near the foot of the post.
But Blues conceded a shoddy goal with 12 minutes to go when a throw from near halfway was flicked on and Jordan Davies managed to turn and wriggle away from the centre-halves to prod across Clayton.
Blues summoned up another big effort to regain the lead.
Fernandez had an audacious curling chip palmed away before playing his part in the clinching goal.
He waited for Miller to sprint past him on an overlap before backheeling the ball into his path; Miller centred first time near the byline and the ball came into Hurst who checked his body to allow it to come across him before planting it emphatically into the bottom corner.
Blues: Clayton, Williams, Roberts, Redmond, Bajrami, Soldevila (Hurst 66), Stirk (Thompson-Sommers 66), Walker, Miller, Fernandez, Andrews.
Subs not used: Concannon, George, Campbell, Rouse.