I think she had to go back to Twin Peaks, everything was right under the surface in Odessa, she needed to get back to dreams and loss/pain, her famous 'homecoming queen' picture and what happened to those dreams, etc.  Sarah Palmer thus smashed that picture when Laura became Carrie Paige in Odessa, abandoning the dreams for the 'happy solution', after Cooper saved her from her death, which resulted in her being torn away and could not meet with the fireman to resume dreams proper(probably because of what is on the last diary page and what she was telling Agent Cooper in the red room), she has to confront whatever it is inside her back at the point of dreams/pain, whatever the secret is that made her scream, probably she will have to go through something like what Agent Cooper was doing this entire series, confront 'Judy', etc..

Was she really off the hook in Odessa?  Laura just accepting everything is great, giving up her dreams, and living with the 'truck drivers' that were making her go mad in Twin Peaks? Thats the most horrific ending I could imagine for her, thus the electric pole here and also when the boy was hit with the truck, Cooper (and Carl) changing the electricity, energy.

Also, Carrie said to Agent Cooper right when he opened the door 'Did you get him?' as if she momentarily knew who Cooper was right away and was waiting for him to get a 'him'.  Maybe still looking for Cooper to catch her killers, truck drivers and community who were torturing her back in Twin Peaks, while turning a blind eye; but now stuck in Odessa, waiting for Cooper to return, who saved her from death, did he finally do what he was supposed to, restore her dreams, etc., after those 25 years of Odessa?   Now Cooper is just starting this, but that she has been waiting for it all this time means that it was still hurting her 'inside'.....