Having pressed the symbol in hopes of her heavy heels reappearing to bring her back down to the ground, Samus frowned as her feet remained firmly planted on the ceiling.
"I should have paid more attention to which one I pressed," she mused aloud. Clearly each of the shapes that now made up the symbol on her Zero Suit did something, but she couldn't quite remember which one had toggled the heels, having been a bit preoccupied with adjusting to becoming a human balloon. While somewhat concerning by itself, she also now had to worry about the shape she'd pressed. If it wasn't the one that activated the heels that kept her grounded, what did it do?
As if in response to her question, Samus suddenly began to hear something odd. It was sort of a trickling sound, like water filling a cup. Had something in the station sprung a leak while she was here? Did she dislodge something when she landed on the ceiling? However, as she looked around to find the source of the noise, the sudden sloshing sound that accompanied the trickling alerted her that the source may be much closer than she thought.
"Is that water... inside of me?" she pondered, placing a hand on her inflated belly. Slowly but surely, she began to feel heavier as the trickling emanated from her body, from her breasts, her stomach, her read, and even her puffy limbs and head. She could not only hear the water, she could feel it sloshing about with every movement she made. Before long, the water began to outweigh whatever gas she'd been filled with, and her feet left the ceiling. With a small gasp of surprise, Samus wiggled about in the air, doing her best to right herself so she'd be able to touch down on her feet, feeling the water shifting inside her as she slowly spun in the air.
As the water continued to fill every part of Samus that the upgrade had inflated, her descent began to grow faster, with more water to weigh her down and yet less gas to hold her up. As a result, Samus found herself unable to correctly orient herself before she reached the floor, landing on her rear with a resounding thud. Strangely, the impact didn't hurt at all, despite the speed at which she was falling by the end. It almost felt like jumping onto a water bed, only the bed was attached to her.
"Well this is... different." With a reasonable amount of effort, Samus managed to pull herself to her feet, feeling much heavier and more bloated than she did before, even before she'd installed the upgrade. The transition had completed by the time she hit the floor, all the gas within her being replaced with water. With no air pocket within her, the water wasn't audibly sloshing anymore, but she could still feel it shifting around as she moved, its weight dragging her along if she tried to move too quickly. Instead of feeling light and airy, as she had previously, she now felt heavy and bogged down. It wasn't entirely unpleasant, though, as the same novelty of being a human balloon still seemed to shine through to Samus, even if she was now a water balloon rather than one filled with helium or something similar. She pressed her hands into her stomach again, finding it to have less give than when she was inflated with air, but still clearly being more malleable than ordinary flesh. She was thankful that at the very least, she didn't seem to be as fragile as an actual balloon, ready to pop and spill her contents everywhere.
Samus hummed in thought as she looked down at the symbol on her Zero Suit again. Unlike with the heels, she remembered which shape of the symbol she pressed to replace her air with water. Pressing it again would presumably drain it out, leaving her light and buoyant again, floating back up to the ceiling again until she could find which shape activated her heels. Of course, now that she was on the ground, there was no need to immediately disengage her current form. Being filled with water was just as fine as being filled with air, surely. There was no harm in testing what the other shapes did while she was a water balloon, was there?