Andreas Thaler
Subscriber
Is a failed repair attempt a reason to be discouraged? No, because this can result in a new project that even brings more than a successful repair!
Valuable and interesting comments to

Nikon Speedlight SB-E: Dissection
I was actually looking forward to the restoration of this little flash to the Nikon EM. Damage to battery acid in the battery compartment gave rise to hope for a major cleaning operation behind the battery contacts, with patching and soldering work on the circuit board. Externally in mint...

have inspired me to a new topic:
When are you successful as a repairer?
The answer seems simple: Whenever you make something that was broken work again.
But what does that mean exactly?
That the broken device is brand new again? Or at least in the state when it still worked? Or is it a success even if, for example, only 50 percent of performance is restored? Can used parts be used for repairs? Does damage when repairing, such as scratches, reduce success?
As a professional repairer
you certainly have less leeway than if you try to repair things for your own pleasure.
Convincing a customer that he should pay for a repair that is only half-successful, possibly with additional damage, will lead to a lawyer either immediately or later. That is clear.
But amateurs
who do that without pressure to succeed?
E.g. the above mentioned broken Nikon Speedlight SB-E that I wanted to repair but couldn't open until I pried it open with force. Of course this can't be named a repair because the flash unit is now completely broken.
But is this a failure that I should be ashamed of? On my workbench or here in the forum?
No, because an attempted repair turned into a dissection that made it possible to uncover and study the individual parts of the device. As it doesn't have to be assembled afterwards (although that would be good exercise anyway).
So, I may learn more than if, in this case, I had repaired the damage caused by leaking battery acid. Because I can do that already.
Of course, it makes a difference
whether I'm working on a device that has material or intangible value to me.
But here I'm thinking about whether I should try to repair it myself or give it to someone who can do it better.
But if, as in this case, it is an inexpensive, defective flash unit, you win without risk in any case: Either the repair is successful, or you have learned something new by dismantling it. Like studying medicine: first you learn anatomy and dissection, then healing.
That's why I recommend not getting discouraged if a repair doesn't work and simply turning it into a new project. The day will come when you can use the experience you gain to actually repair this device.