HestaPi stuck at 0°-screen (no. 15 of First boot ONE-tutorial)

It seems you have upgraded after you used the HestiaPi image.
The whitelist issue is something that appeared in 2.5 and therefore it is not merged in the official release.
Please use this workaround or simply don’t upgrade yet.
Everything you reported should go with this… btw the CPU load was indeed fine. It is just the UI that confuses during startup (maybe we should delay the first check of CPU load)