I know I'm late to answer here, but I figured I'd post (if anything for other people who might read this later.)
Yes, you technically could swap CPUs in phones (provided that the CPU's have the same BGA layout and basic power/voltage specifications.) You would also have to reflash the firmware on the eMMC storage chip to get a different CPU to boot assuming the motherboard is capable. But, the realistic answer is no, don't even try this or you will ruin both devices.
Cell phone CPUs are soldered on to the motherboard with a ball-grid array (BGA) which means the CPU has hundreds of tiny solder balls connecting it to the motherboard. You could change the CPU by heating up the solder balls under the CPU (a heat gun works, but a BGA soldering station is needed to be able to control the heat.)
You must get the solder balls under the CPU hot enough to melt so you can remove the CPU without ripping out the tiny metal traces (wires inside the PCB board.) If you rip out the traces because the solder balls weren't fully melted then the motherboard is trash (I've done this before.) You also have to be careful not to get the CPU or other nearby components too hot that it'll damage them... really you need ~$500 BGA soldering workstation and practice doing this to be successful. Once you've removed the CPU, you would need new BGA solder balls to reconnect it to a different phone board (63% tin/37% lead are good; also need correct diameter ball for the CPU type.) You'd want a to get a BGA stencil (they sell them specifically for different CPU types, or you can cut them to shape) these stencils are put over the back of the cleaned CPU so you can drop solder balls onto it and they'll fall into place on the CPU, then you heat them to melt into place, let cool and carefully remove the stencil (there are different ways of doing this.) Ultimately you have new solder balls attached to the CPU that you can then place on the motherboard and solder the balls into place (securing the CPU.)
Now this Alcatel Fierce 2 (I think) uses Qualcomm's Snapdragon 210 (MSM8909) while you're Samsung Galaxy Note 4 uses either Qualcomm's Snapdragon 805 (quad core) or it uses Samsung's Exynos (octa core.) I doubt Exynos would even fit on the Snapdragon's BGA... and I'm not sure if those two different Qualcomm CPUs have the same size BGA or not (they're both quad core Snapdragons, so it's possible.) But even if both CPUs used the same BGA connection and you switched them (assuming you did everything correctly, which is unlikely because it's not easy) then all you would have is two phones with the wrong CPUs in them lol. I doubt either phone would boot because the firmware would be looking for the original CPU and it would fail to boot without it. Now if you could unlock the bootloader (difficult to do with most phones) then you could flash the proper bootloader firmware for the replaced CPU... in this case it would probably work. If you can't unlock the bootloader (must be done before the original CPU is removed) then you could (or would have to) replace the eMMC storge chip with a similar one that's been flashed with the correct bootloader firmware for your CPU replacement. eMMC storage chips are BGA just like the CPUs... but they're much more sensitive to heat and some of them have the RAM modules built inside the same chip as the NV (non-volatile) storage.
But the Fierce 2 doesn't have a bad CPU... what it needs is more RAM (only has 1GB RAM) and the firmware is terrible on all Alcatel phones. If you could root your Fierce 2 (should be doable, at least if the firmware hasn't been "updated"... if it has, then the vulnerabilities you'd need to exploit it to gain root are likely patched and you'd be left with finding a new exploit or flashing the eMMC with Qualcomm's QFIL.) But if you gained root access to this phone, you could modify some of the kernel settings that really hold this phone's hardware capabilities back; plus you'd be able to remove Alcatel's (TCL's) bloat system apps and free up some of your small 4GB internal storage.
Please don't try switching the CPUs... it won't work out well. But it is technically possible (for some devices anyways.)
If you still have this Alcatel phone and want to try improving it's performance via software modifications, let me know because I'm working with a similar model Alcatel phone right now and I'm looking to collect some information (full model numbers) from other Alcatel phones so I can write some additions to a python script for fetching Alcatel's firmwares (so people can unbrick and root their Alcatel phones more easily.) Since Alcatel doesn't make their firmware available very easily, I've decided to try and make it easier for people. Though I highly recommend to anyone reading this **NOT** to buy any phones from Alcatel (AKA "TCL") these phones have terrible software and the bootloaders are locked down with the fastboot partition completely removed (ie you can't make any changes to these phones terrible system files or remove any of it's spyware.)
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