Flashing firmware, when to use preloader?

I have updated the firmware to my Zblaze Thor twice. With both tries if I unchecked the “preloader” nothing would happen after selecting download and connecting the watch. After removing watch I selected the “preloader” box hit download reconnected the watch and the firmware updated. I have not had any noticeable problems with the operation of the watch after either update. 
I see several mentions in updating posts about  “not” using the preloader and would like to know when to or not to use it and why.

I would still like an answer to my initial question, please. When do you use it or not use it and why? There must be a reason for telling us not to load the “preloader.” I did the google search and you can come up with as many directions to use it as to not use it, with none of the one’s I found definitive without reading something into their suggestions. Maybe a better explanation on what the preloader does and how to use it. I obviously needed to use it as the firmware would not install on my watch unless I selected it first. If that is not the case, how should I install the firmware without selecting the preloader?

Jul 30, 2017 14:49:41 GMT 1 capt jon said:
I have updated the firmware to my Zblaze Thor twice. With both tries if I unchecked the "preloader" nothing would happen after selecting download and connecting the watch. After removing watch I selected the "preloader" box hit download reconnected the watch and the firmware updated. I have not had any noticeable problems with the operation of the watch after either update.  I see several mentions in updating posts about  "not" using the preloader and would like to know when to or not to use it and why.

Hello, After flashing a wrong preloader, your watch will be completely dead .. We cannot help for you than... I'v flashed many times on my phones, watches, boxes. Without that all working properly too. This why we say alltime : dont flash that. Anyway when you 110% sure that match for your watch, nothing wrong happen, risiko is your choice. Just google search about : Flashing firmware, with or without preloader.