different meanings of скучать
I know that скычать по кому-нибудь means to miss someone. But I just saw скучать от кого-нибудь and скучать за кем-нибудь. What do they mean? Does скучать от кого-нибудь mean to be bored or tired of someone?

Question

different meanings of скучать 
I know that скычать по кому-нибудь means to miss someone. But I just saw скучать от кого-нибудь and скучать за кем-нибудь. What do they mean? Does скучать от кого-нибудь mean to be bored or tired of someone?

Answer

"Мо́чи нет" is not from "не мочь"(be unable). Мочь (archaic for мощь) a noun and means "strength, power". So "мОчи нет" simple means "[there is / I have] no strength".

Answer

"он мне наскучил" is VERY bookish. No one says so in colloquial language.

"скучать за кем-нибудь" is an ukrainism. Also people in the south speak like that.

"скучать от кого-нибудь" is incorrect.

Answer

Примеры:
1. Скучать от чего, где. 
Скучать от безделья. Скучать в гостях. Скучать на новом месте. 

2. Скучать о ком-чём, по ком-чём, по кому-чему.
 Скучать  по дому.  Скучать  по семье. Скучать без друзей. Он по тебе скучает. Я по тебе скучаю.

Answer

The examples you found are incorrect. There is a single correct way is скучать по кому-нибудь, forget the other variations and use it.
Look perhaps you understood meaning wrong. Скучать от конго-нибудь it is mean the condition when someone makes you feel bored, but we can't use the same words to express it.
In English that sounds like "He makes me bore or His lecture made me tired"
                                        "Он скучный; мне скучно из-за него; его разговор меня утомил"

Answer

One example 

Но узнаю по всем приметам '''''''''''''''''' 07 '''''''''''' 07 ''''''''''''' I recognize all sings of fleeting 
Болезнь любви в душе моей: '''''''''''''''' 08 ''''''''''''' 08 ''''''''''''' Disease of soul. Love, I mean. 
Без вас мне скучно, - я зеваю; ''''''''''''''''' 09 x 10 ''''''''''''''''''' And I feel sad with you - I'm quiet, 
При вас мне грустно, - я терплю; '''''''''' 10 x 09 '''''''''''''''''''' I'm bored without you - I yawn, 
И, мо́чи нет, сказать желаю, ''''''''''''''''' 11 ''''''''''''' 11'''''''''''''''' I have a great and strong desire 
Мой ангел, как я вас люблю! '''''''''''''''''' 12 ''''''''''''' 12 ''''''''''''' To say, my Angel, I'm all yours. 

Пушкин А.С., "Признание" .................................... "Confession" by Alexander Pushkin 
......................................................................................... (Translated by Slobodyanik Lada) 

N.B. Order of the lines is not the same for the original text and the translation. 

http://www.russianlegacy.com/en/go_to/culture/poetry/pushkin/confession.htm 

P.S. (postscriptum has been removed)
P.P.S. Sorry, for my non-correct post scriptum. 
Please read suggestion by Lodka. 
(to lodka: sorry, and thank you for your comment)

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