Based on the game 'One Chance'

The BoBoiBoy personalities are mortals, or humans.

After lots of trials and researches, Solar had managed to make a successful concoction that can help stabilize their powers.

Upon ingestion, Solar found out that in trying to stabilize their powers, the concoction connects their powers to their mortal bodies.

It made using and controlling their powers more efficient.

However, the mortal body isn't made to sustain that kind of power.

Their powers became cancerous to them. They will die soon, depending on which element they are most exposed.

Removing the watch will be useless since all of their powers are already connected to their bodies.

All of the personalities are suffering. They were lucky that it was only them who had drunk the concoction.

Solar was found kneeling in front of his brothers, crying and apologizing profusely. His brother understood his situation and forgave him, but Solar, due to his pride, wasn't accepting any of it.

Thunderstorm had enough of it after Solar had apologized for the hundredth time. He pinned Solar to the wall and firmly told him that he's forgiven and that 'I don't want any more apologies hearing from your mouth or else you'll be dead before your time.'

Solar finally accepted that his brother forgave him and instead dedicated his time trying to search for an antidote.

The rest of the gang were confused as to why the personalities were suddenly afraid of their own elements. They were horrified when they found out and resolved to help Solar in finding the antidote for it.

Cyclone was the first one to die. He started to have difficulty breathing a few days after their powers became cancerous to them. One day, he just stopped breathing.

Solar, grief-stricken, doubled his efforts in searching for the antidote. He was barely eating and sleeping that Quake literally had to force him to eat and sleep.

Ice followed the wind elemental. Since water is an essential part of daily lives (and ice is still part-water), he drowned from the condensed water vapor that he inhales.

Quake was next. Since they were on Earth, he's really exposed to the land, despite being isolated inside the house. His strength deteriorated and one day, he just collapsed.

After Quake died, no one had the heart to force Solar to do anything else. He literally spent day and night in his dark room, which was only bright enough for him to see.

Thorn died by being poisoned in one of the plants. The plant itself wasn't even venomous.

Blaze didn't evade his fate as well. The constant use of fires while cooking increases his body temperature. He was literally burned inside out.

In the end, it was only Thunderstorm and Solar left among the elements.

It was raining heavily outside, with the occasional clap of thunder.

Thunderstorm went into Solar's room and collapsed upon entering.

He saw Solar crying on the floor, holding a small bottle in his hands.

Like Thunderstorm, Solar was already weak.

Solar showed him the finished antidote, which was made with the help of the gang.

"We could end our suffering."

Thunderstorm looked conflicted, as does Solar.

The next day, Tok Aba (who was also aware of the situation) found two bodies lying dead inside Solar's room. One looks singed while the other unseeing.